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7md5cq | How do humans almost always know the "perfect" amount of power to place on a throw to get the object to it's intended target? | Biology | explainlikeimfive | {
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"Generations of natural selection. Back in the day, if you wanted to eat but couldn't aim accurately, you'd never be able to survive as a professional baseball player.",
"Practice. For every football you see hit some receiver (for example) 50 yards away, there were 10,000 missed passes. Over time humans develop a sense what they can accomplish after doing it so many times over and over."
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7md66o | How does animal agriculture (particularly cows) contribute to a bad environment? | Vegans always say to go vegan for the environment...but how does the animal industry affect the environment? | Biology | explainlikeimfive | {
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"Cows fart a lot, like an amount equal in size to their body every day. Farts are mostly methane, methane is one of the worst greenhouse gases. The sheer number of cows required to sustain the U.S. beef industry is enough that there is a permanent cloud of farts swirling over the four-corners area that is visible from space (with the right sensors), even though there are relatively few humans living in the area. Secondly, the beef industry is incredibly resource intensive. Beef uses much more water and food per pound than other meats. I personally am not a vegan, but even though I love beef, I try to eat more chicken because of the lower environmental impact associated with poultry farming when compared to beef.",
"In addition to waste, deforestation and such, cows eat. A lot. About half of all grain produced in the US and 40% worldwide goes to livestock. And you need a *lot* of water to grow all that grain and hay cows eat. It takes approximately 100K liters of water to produce one kilogram of beef (compared to 3.5K for 1kg of chicken and 500 for 1kg of potatoes) On average, animal protein needs 8 times more fossil fuel to produce than plant protein, and is only 1.4 times more nutritious for humans. On average it takes 6kg of plant protein to make 1kg of animal protein. The current system is utterly unsustainable and an enormous amount of food and water and energy is wasted. Read more: URL_0",
"Cows let off a large amount of methane (which is a greenhouse gas) throughout their lives. In addition, the high demand for beef in recent decades has led to large deforestation issues around the world. This reduces the CO2 absorbing trees as well. So cattle farming not only release greenhouse gases into the air, but also raising cattles has meant cutting down trees that take in another greenhouse gas as well.",
"The World Bank estimates that [91% of the land deforested in the Amazon since 1970 has been cleared for grazing]( URL_2 ). Raising cattle for food requires far more land than growing plant-based foods directly for consumption. It also is a substantial contributor to greenhouse gas emissions, [a bigger share than all of transportation according to the UN]( URL_0 ). However, those aren't the only areas of serious concern. The UN has also stated: > The livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global. The findings of this report suggest that it should be a major policy focus when dealing with problems of land degradation, climate change and air pollution, water shortage and water pollution and loss of biodiversity. > Livestock's contribution to environmental problems is on a massive scale and its potential contribution to their solution is equally large. The impact is so significant that it needs to be addressed with urgency. Major reductions in impact could be achieved at reasonable cost. [Source](ftp:// URL_1 )",
"TL;DR cow farts are brutal and unbreathable also they take up to much our water which should be put to better use."
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7md9fs | Why can’t humans with excess weight survive off of stored fat? | Biology | explainlikeimfive | {
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"Fat is exclusively made from carbon, oxygen, and hydrogen. The body needs more nutrients than that to survive and function properly, elements like nitrogen, phosphorus, sulfur, sodium, potassium, calcium, iron, zinc, magnesium, etc. are required for the body to work properly. Fat can only provide three of all the required elements. It is possible to go without eating and only taking nutritional supplements to make for the lack of other elements besides C, O, and H, but it isn't advisable.",
"Mostly you can, but there's issues around the nutritional value. Because fat is a high energy storage medium, it's great at holding energy you need to run... But not so awesome at storing other things like vitamin C, for instance. So you won't necessarily starve, but malnutrition is a factor."
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7md9x0 | Why do people pull their windshield wipers up during a snow storm? | Chemistry | explainlikeimfive | {
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"text": [
"To prevent the wipers from becoming frozen onto the windshield glass, if ice forms due to snow melting and refreezing."
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7mda6o | How does fish oil help fight heart disease? | Biology | explainlikeimfive | {
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"Fish oil supplements contain omega-3 fatty acids like docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). It's been shown that these compounds can lower circulating triglyceride and blood cholesterol levels, which reduce your chances of developing heart diseases. [Source] ( URL_0 )"
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7mddun | Store brand and Name brand medicine | Mucinex is double the price of the local drug store's brsnd of severe cold and flu cough syrup, however they have the same increments of the same ingredients. | Chemistry | explainlikeimfive | {
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"It's called a generic formula. Anyone can produce it and sell it. Tylenol is brand name. Acetaminophen is the chemical that Tylenol and generics contain. Thats the medicine. Why 2x price? Because profit from name recognition.",
"It depends on the medication. For some of them it's a matter of the inactive ingredients contained, for some it's just a matter of bottle labeling. And for some it's about the selectivity of the medication. See, a lot of the chemicals in drugs are what are called \"enantiomeric molecules\" which means that they can, while having the same atoms attached to the same atoms, have remarkably different properties based on configuration. Think of it like your right and left feet; both have five toes, a heel, ankle, and leg attached, but no matter how you twist them they will never look identical. And you can't comfortably put your right foot in your left shoe or vice-versa. It's the same with enantiomers. For a molecule, it being in the left configuration might alleviate your congestion, but the right configuration might do nothing (or possibly have adverse effects.) So the name-brand medicine selectively produces (or filters) so that their 50 mg pill contains ONLY left configuration molecules, whereas the generic brand may not filter or selectively produce, causing to to be slightly less effective.",
"For the most part they are identical, however there can be differences between the filler materials used, which can have unwanted effects on some people. Sometimes the name brand may be designed in a way that makes it easier to ingest (IIRC some drugs may use a sugar coating to make them more palatable)."
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7mdkuh | How does a computer recover corrupted data? | Technology | explainlikeimfive | {
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"Tolerances, error detection and error correction. Tolerance: In TTL logic if the voltage on a data line is between 2V and 5V that's a logical 1, and between 0V and 0.8V is a logical 0. This means that the hardware can take a bit of variation and it makes no difference. This is by the way why expensive cables for digital data are nonsense -- unlike with analog, 4.5V and 5V are exactly just as good. Error detection: Take 8 bits, let's say 10011100. Then add an extra parity bit. When the number of 1s in the byte is even, parity is 0. When odd, parity is 1. If one bit flips now parity is wrong, and we know something went wrong somewhere. Error correction: With a slightly more complex system we can detect where something has gone wrong. Since we know the position, we know that the bit must have flipped, so we flip it back and problem solved. Easy example of error correction: We take a group of 8 bytes and write them down on one line each, then we calculate the parity for both rows and columns: 01100011 0 01101111 0 01101101 1 01110000 1 01110101 1 01110100 0 01100101 0 01110010 0 00000111 Now flip a bit somewhere: 01100011 0 01101111 0 01101101 1 01110010 1 < -- 01110101 1 01110100 0 01100101 0 01110010 0 00000111 ^ Now if you check the parity it'll be wrong on one row and one column, so we know where in the table the error can be found. Flip it around, and fixed! There are better methods of course, but this one is easy to explain. CDs and DVDs specifically have several levels of error correction, so that it can handle both small local mistakes, and large scratches on the surface. Now if that wasn't enough, then it really doesn't really deal with it, and you have corruption for good. Some programs can deal with an amount of it (eg, it can be tolerable for audio or video), some break badly."
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7mdsf0 | Why is blue light from screens harmful and strenuous on our eyes, while blue objects in the environment, are not? | Biology | explainlikeimfive | {
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"The issue is that screens shine blue-rich light straight into our eyes, When we are outside, the light is mainly sunshine, which is green-rich. The other problem is this blue light acts like sunshine to our brains, telling them that it is still daytime, and that we should remain alert and awake. If you are using your device late at night, this is going to mess up your sleep. Blue light in the daytime is fine, because it's good to be awake in the daytime. And blue items in your room are only lit by what lights you have - generally more yellow-rich warm white lighting fixtures - and are a whole lot dimmer.",
"TL;DR: This has very little to do with *color* and a whole lot to do with *brightness*. Screens are bright emitters of light. Objects in the environment, regardless of their color, are not. Screens are active light sources, i.e., they *emit* electromagnetic radiation in the visible spectrum (i.e., visible light). Blue light is on the higher-frequency end of the visible spectrum, and higher frequencies are, for lack of a simpler term, more \"energetic\" than lower ones. It's not that blue light is *actively harmful*, but it's definitely the case that it's bad for your night vision and thus not very compatible with rest/sleep. Further, because they're active light sources, they're going to be *brighter* than objects that merely reflect light (more about that in a minute). Looking at bright light sources can produce eye-strain after a while, but that effect isn't limited to sources that are brighter on the bluer end of the spectrum. Even a sufficiently bright *red* light will produce eye strain, if you look at it long enough. But generally speaking, most objects are passive light sources, i.e., they *reflect* light from other sources, but they do not themselves *emit* light. By definition, reflected light cannot be brighter than the source which emitted it, so most passive light sources are going to be necessarily dimmer than most active light sources. Often quite a *bit* dimmer, as most objects absorb at least as much light as they reflect, both across the spectrum and for any given piece thereof. So a blue object really isn't going to be all that hard to just look at, as it's not going to be bright enough to produce the kind of eye strain you appear to have in mind."
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7mdu9u | why does sound from headphones sound good next to my ear but terrible and tinny when I'm far away? | Physics | explainlikeimfive | {
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"The speaker membrane is basically an air pump that moves air back and forth to produce sound. The movement of air creates pressure on our ear drums, which is what we can hear. For high frequencies, it only needs to move a tiny amount of air, but do it many times per second, but for lower frequencies it needs to move a large amount of air, fewer times per second. That's why bass speakers are large and speakers for high frequencies very small. Headphones however only have a small speaker, so they have to a trick to reproduce low frequencies: Instead of moving the air back and forth, they just pressurize and depressurize the air between the speaker and the ear drums. This way, the air pushes against the speaker membrane, creating far more sound energy in the process than if the air can just move freely like in a regular speaker. But if you remove the headphones from the ears, this pressure can just go away, and the headphones lose their ability to produce low frequencies. That is what causes the tinny sound. Imagine this a bit like using a bicycle pump: If you connect it to an empty tire, it's very easy to move the pump because the air can just easily move out of the hose and fill the tire. But if the tire is already full of air, it becomes very difficult to pump, costing you far more energy each stroke and in turn putting more energy into the tire."
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7mdyve | Why do airplanes have double-pronged audio jacks? | Technology | explainlikeimfive | {
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"I suspect there's also the opportunity to make you use, and charge you for, their headset instead of your own."
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7me2c0 | What is eye goop? Why does it form in the corner of our eyes and why only after a nap? | Biology | explainlikeimfive | {
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"text": [
"Your eyes naturally keep themselves moist. That’s why we blink. Eye goop is simply an accumulation of this lubricant. Hard goop = dried up mucus. Pretty much, they’re boogers."
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7me5ki | Why does our pain threshold increase as we get older? | If the question is a little unclear allow me to explain, if I used the exact same force ( just assume it for the sake of argument ) and punch a fully grown man in the stomach he may react a little and wince, but then if I apply that force instead to a 4 year old in the stomach (s)he would probably be in tears on the floor, what actually changes to increase our pain threshold as we grow older? | Biology | explainlikeimfive | {
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"Pain tolerance is mostly about having a scale of pain in your memories to call from and compare to. Children don't know that the splinter in their finger isn't that big a deal, it is the worst thing that they have encountered in their entire life. The older you get, the more painful stuff you experience, until everyday things like stubbing a toe or bumping your head just don't measure up to the worst stuff you've experienced.",
"Our muscles get stronger as we get older. And our instincts are sharper. If you go to punch a man on the stomach, he will instinctively tense his stomach muscles and prepare for the punch. A child won't (possibly?) I dont think it increases with age, but only from a personal point of view. I used to run about and bruise and fall as a child. But now if I bump or bruise myself by accident as an adult it feels worse. I also dislocated my thumb when I was 8 and popped it back into place there and then without a care. When it happened at 15 I was in pain, and to hospital for help."
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7me9iy | What makes contagious diseases/illnesses contagious? | Biology | explainlikeimfive | {
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"Pathogens expresses things called virulence factors which help them in spreading and colonising new hosts and causing disease. Some examples of these would be adhesins (which help the pathogen stick to the host) and toxins (which disrupt the host normal function, giving the pathogen a foot hold). The more virulence factors a pathogen has the easier it can spread"
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7mebn8 | How do electronics that rotate stay connected? | For example, a PTZ (Pan Tilt Zoom) camera can keep rotating indefinitely, yet it's always connected for video and power. If the rotating component of the camera was connected to the static part with wires, it would just twist and break, so how does the camera transmit images and use electricity? | Technology | explainlikeimfive | {
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"As a basic example, imagine a headphone jack plug in its socket. The jack plug is split into 2 or 3 segments which carry different signals, the socket has 3 contacts inside it which always touch these segments on the jack plug, and you can rotate it as much as you want. There is lots of ways to do it. [here]( URL_0 ) is an image to demonstrate. See how it has 3 stacked ‘PCB’s, and each PCB has a little prong which touches the jack plug in a specific area. I believe that image is of a TS (tip, sleeve) jack so it only has two contact points. One on the main shaft of the jack and one hooking down to touch the tip. There is also TRS jacks (Tip, ring, sleeve) these would have an extra bit similar to the hook which touches the ‘ring’. This is sounding very NSFW. Theoretically you could have a jack split into 100 segments with 100 contacts coming down to meet it.",
"The PTZ cameras I use at work can't continuously rotate, but there are a few ways this can happen. 1. Use slip rings and brushes as described by u/jgpirie. The problem with slip rings and brushes is size, cost, and reliability. In a VCR, they would use precision slip rings and brushes with multiple wire contacts. 2. Use a rotary transformer. These were used in VCRs to get the signal to and from the rotating heads. They would not work well with analog video which needs frequency response from DC to a few MHz. The signal would need to be modulated into an RF signal. Slip rings would still be needed for power. 3. Use a camera which is stationary and uses a 360 degree mirror. [Like this.]( URL_0 ). The image has to be processed in software. The result is pretty poor, but has been used. One advantage is that it has no moving parts. 4. Use an optical transmit and receive system with slip rings for power."
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7mecd4 | How did google aquire the 8.8.8.8(google's dns server) ip adress? | Technology | explainlikeimfive | {
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"text": [
"If you do a Whois lookup (Whois IP 8.8.8.8). Level 3 Communications, Inc. owns the Class A Subnet 8.0.0.0 And Google is listed for the Class C Subnet 8.8.8.0 My guess is Google leased that Class C from Level 3 Comm. and decided to use it for their DNS server to make it easy to remember."
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7mew3c | Standards for measurement units (time, length, etc) have developed so that they become more accurate than the one made before. But how can people find out that their new standards is more accurate than the one before if that was the standard? | Physics | explainlikeimfive | {
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"It isn't that they are more *accurate* but that they are more *precise* in the sense that they: A) define a standard of measure to a greater degree of precision (more significant digits); and B) are based more firmly in fundamental constants (such as the speed of light).",
"It is more about precision than accuracy. Accuracy is how close to the \"real\" thing. Precision is how much does it varies. When the standard is a physical object, it can change size due to temperature and pressure. When the units are derived by some natural phenomena, like the radiation periods of some atoms, there is a guarantee that it will be the same for everyone every time.",
"The thing is, they don't. They don't just figure out that they are more accurate, they SET the new time/length/mass, etc. This is to make things more convenient for science. Take an example: the meter, for instance, measuring distance. IIRC, the SI measurement system (System Internationale in French or something) defined the meter as one ten millionth of the length from the North Pole to the Equator, following a meridian (a path on the same longitude). Before that, I think they had a physical bar from which to measure a meter from, but like a physical kilogram, that was scrapped. In the 1900s it was defined as the distance that light travels in 1/299,792,458th of a second. This is how they define a meter, a second, and light. By doing this, you aren't trying to \"catch up\" to the right measurement of either of those things based on the standards you set previously. Scientists first defined the second as the time it takes for a Cesium atom to vibrate ~9.2 billion times. Then they measured, using their previous standards, how long a meter was: something close to how much light travels in about the same time as the above. Then they narrowed it down to a nice integer, and now you have a good standard",
"Accuracy is being closer to the true target. In this case, whatever the truth of the measurement value is. Precision is how often you can do that. For example, you can be precise and hit a bullseye on a dartboard. Once. To be precise you need to be able to replicate this on demand at a dependable rate. (I hit 8/10 clay pigeons is accuracy and precision.) I hit the one clay pigeon is accuracy. When transferring this to increasing standards of measurement, you can increase accuracy, but it's only useful if replicable. If centimeters were the best humanity could manage then discovering millimeters would be an increase in accuracy, but it wouldn't have been adopted if it couldn't be replicated dependably. Edit: the clay pigeon may not be a great analogy. If you always hit a dart board you have a ratio of precision. Always hitting the bullseye is precise too, but more accurate."
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7mf6p0 | If white light is split when refracted, then why does our eye not see it like many different colours? | Physics | explainlikeimfive | {
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"It's not too clear exactly what you're trying to ask.. but I Think you're saying \" If refraction leads to different colours being split, then why don't se see loads of different colours when we look into white light. \" If this is what you're asking, the answer is... we kind of do. The severity of colour components splitting out is proportional to how much the light is refracting. It is called dispersion. So middle of a, say, lens, has very small dispersion, while the edge of a lens will typically have much more severe dispersion. In an imaging system like your eye or camera lens, it will generally lead to different colour components within the picture being a very slightly different scale factor. If you wear glasses and have really bad eyes, the edge of your vision will often have the colour components being split out. There are ways around it: Camera lenses are designed to minimize this by using many lenses together with different amounts of dispersion. After this, you can just scale the colour component images slightly to compensate. For your naked eyes, it doesn't really matter because the dispersion is small for the center of your vision. For the edge of your vision, there is very little detail, so the dispersion doesn't really matter."
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7mfadc | How do astronomers describe where things are in space when the Earth, Sun and whatever object they are observing are moving? | Physics | explainlikeimfive | {
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"Yes, things are moving, but they are very, very, very far apart. that means that there relative motion is only a small percentage of the distance. Most measurements are made in the equatorial coordinate system called ascensio recta or right ascension. With declination, it makes a system like longitude and latitude. The \"equator\" is the plane of the Earth's orbit around the Sun. The Earth's north pole is inclined (giving the Earth seasons) but celestial North is the direction that's 90˚ from the Earth-Sun plane using the same right hand rules as we use on the planet. Declination is the equivalent of \"latitude\", how far an object is above the Earth-Sun plane. The \"prime meridian\" points toward the Sun at the vernal equinox. Measured from there, right ascension is the \"longitude\". It's usually measured in hours, where 00h = 24h. Stars move up and down as they rise and fall, so this \"time-like\" angle measurement reflects when they are at the highest part in their arc using the Earth as a giant protractor.",
"You define your coordinate system defined using some reference object. It applies not just to astronomy but almost every description of moving things. If you're a machine tool, and you want to describe where you should move, you might start with the description given in the coordinate system fixed to the part you're trying to cut. Satellite is conveniently described using the earth. The former 2 examples are not very useful if you describe it with a coordinate system fixed to our galaxy, so generally you wouldn't do this even if it's technically right. Astronomical objects often do though! So the absolute position often gets referenced to us. So some start will generally be described as x light years away from us. Unlike linear movement, rotational movement does have an absolute 0. ie, its not possible to say A is absolutely stationary; only relatively stationary ocmpared to something else. But rotational movement can be absolutely 0. So for astronomy, for stars far far away, we'd probably use a coordinate system with us as origin, which is not rotating. also: URL_0"
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7mfn3y | Market capitalization when it comes to purchasing a company. | Here is my understanding of market capitalization: outstanding shares x stock price = market cap. The market cap is in essence the value of the company. Recently Humana announced they would be buying Kindred Healthcare for $4.1B. Kindred's market cap is $822M at the time of this writing. Wouldn't that mean that Humana is paying more than 4x what Kindred is actually worth? I'm so confused. Please ELI5. Thank you in advance! | Economics | explainlikeimfive | {
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"Often the buying company must pay a premium to the traded price, to acquire the company, but usually this premium is 20-50% of the pre-offer share price. One thing that isn't in the market cap but is usually part of the purchase price is the assumption of debt. If Kindred owed roughly $3.3 billion to its creditors, the purchase price could be $4.1 billion with only $800 million going to shareholders. The idea being the purchase of two otherwise identical businesses, one financed by mostly equity while another financed by mostly debt should probably have the same purchase price. I didn't see the deal press release, but did find an article with this: > Kindred, which had $7 billion in revenues last year, has been weighed down with *$3.2 billion in long-term debt.* So Humana is paying $800ish million for the equity in Kindred Healthcare, but also will have to repay Kindred's creditors $3.2 billion. It's fairly common to include both of these when reporting the amount spent on a merger. Whoa, thanks for the gold!",
"There are many different ways to value an asset, be that a house, a single square of toilet paper, or a company. At any given moment, the different ways to value an asset can be equal or vastly different. However, the actual price of something at any given time is the intersection of supply and demand. In terms of valuation there are many ways to value something. * There's **replacement cost**: how much money would I need to spend to replace this exact asset at this particular moment in time with another of the same quality. Car insurance companies use this when valuing your car in case it gets 'totaled'. A car is totaled when the cost to repair it is greater than the cost to buy a similar car (before the damage) on the open market. This is why a 15 year old car with 250k miles on it can be totaled after a fender-bender. A insurance company would prefer to pay the $900 to buy a comparable copy of your car versus what it would cost to repair it. Let's look at a bottle of water as an example. I can buy a bottle of water at a gas station for $1.19. If I walk out of a gas station after purchasing a bottle of water and it gets stolen, the replacement cost of that bottle will be another $1.19 plus the effort it takes to go back inside and retrieve another one. * **Market Capitalization** is exactly what you described. The number of outstanding shares times the price per share. For public companies, this price is the aggregate of all publicly available knowledge about a company's value. In layman's terms, this means that across however millions of shareholders a company has, their collective average valuation of that company at any given picosecond is the market capitalization at that moment. Since a Market Cap is the crowdsourced valuation of a company, it will include things that don't affect other types of valuations. Wall Street's perception about who's running a corporation, where the company is incorporated, how many (and how serious) pending lawsuits it may be exposed to all affect how people perceive a company's current value (or, more importantly, how they think it will be valued in the future). This is why companies like Tesla have a huge market capitalization relative to the value of their physical assets. People *think* Tesla will be more valuable in the future than it is today, so its market capitalization is nearly equal to a physically much larger car manufacturer like General Motors. Using our water bottle example, Market Capitalization would be like getting a million people into a room and asking everyone how much each would pay for one water bottle ($1.19). Then taking their average price to determine the value of 100,000 water bottles ($119,000). * There's also **intrinsic value** which takes into account how a company generates cash. Value investors calculate a company's intrinsic value and compare it to the market cap to see if a company is over or undervalued at any given time. If I own a 100 water bottles, using the market capitalization method I have $119 worth of assets. But, if in real life I am selling those bottles for $2 each, my assets are worth much more than what my market cap is suggesting. My intrinsic value, in this example would be much higher than $119 because the cash I generate from my assets is higher than what the market gives me credit for. Finally, we come to price in the real world. Buyers of public companies almost always need to pay more than the market cap for a number of reasons. One, you need to convince the target's shareholders to actually sell their stock. Remember, a company's current price is the aggregate of the collective knowledge of its shareholders. This means that a company's shareholder are, at any given time, happy with their expectation of prices. No one would continue to own a share of a company if they *think* the price was going to get worse, they all continue to own shares because they think the price will increase. So, to purchase all of the shares of another company, you have to buy them for more than what the average shareholder thinks they're going to be worth. Second, a market cap is the valuation of a company given all publicly available information. Publicly available is a key distinction. All companies have trade secrets, secret product development pipelines, and their own secret sauce that only they know about and control. The secret sides of a company are sometimes called 'goodwill' on a balance sheet because its made up of things that aren't able to be easily valued. In pharmaceuticals, the difference between physical value and goodwill can be extreme and nearly impossible to valuate. The cure to the common cold could make a small lab of five researchers worth billions of dollars. But, if they fail to get their promising drug past FDA regulations, they're literally worthless. Finally, there are a host of other reasons to pay more for a company. Maybe you're paying gobs of money for a company because you don't want your competitor to purchase them. Maybe they have a key patent to a widget that you want to include in your next gadget and without the rights to that widget, your gadget is worthless. Or maybe you're under intense pressure from your own shareholders to grow your company and Company Z is up for sale. This gets us to supply and demand and real price. Humana is spending $4.1 billion on Kindred because Kindred is worth $4.1 billion to Humana. All of Humana's internal valuations of Kindred's product line, services, people, patents, and more sum up to $4.1 billion (or more). Kindred's selling to Humana because their internal valuation of all of those things is $4.1 billion (or less)."
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7mfnw5 | What is the ifference between neuralgia, neuropathy and neuropathic pain? | I'm finding it really difficult to find the difference between the three but as I've come to understand they exist as three different definitions within medical literature. Any help would suffice, Thank you. | Biology | explainlikeimfive | {
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"Neuropathy basically means \"something is wrong with your nerves requiring medical treatment\" Neuralgia is nerve *pain* specifically. So that's a possible symptom of neuropathy. Neuropathic pain is basically the same thing but with more letters.",
"As I understand: neuropathy- any condition affecting the nerves neuropathic pain- pain caused by some kind of neuropathy neuralgia- synonymous with neuropathic pain, but from what I've seen is often used as a more of a descriptor of conditions involving specific nerves/nerve bundles (eg: trigeminal neuralgia) that lead to neuropathic pain. I may be wrong though so if anyone knows for sure, let me know!"
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7mfr9l | Why does the straw keep rising to the top when in a carbonated drink? | Physics | explainlikeimfive | {
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"text": [
"The bubbles stick to the straw and rise him up. its like a balloon filled with air in a swimming pool"
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7mfv9g | why change in sunrise and set do not change equally each day | Looking at the weather I noticed that sunset gets later faster than the sunrise times gets earlier. Is there an easy explanation as I thought it would equal change in the times of the events each day. | Physics | explainlikeimfive | {
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"They change equally compared to the time of solar noon (when the sun is highest in the sky), but solar noon also varies. Earth's orbital speed varies through the year, and that makes the length of a solar day vary slightly through the year. When the solar day is less than 24 hours, noon gets a bit earlier each day. When it's longer than 24 hours, noon gets a bit later each day.",
"The earth orbits the sun in an ellipse - it's farthest from the sun in July and closest in January. Thanks to some complicated math worked out by Johannes Kepler, we know that orbits follow the \"law of areas\" - basically, the wedge that an orbiting body sweeps out will have the same area for equal amounts of time (if you draw the earth's orbit and tick off each day along it, then connect each tick mark to the sun, the wedges will all have the same area). With the law of areas in mind, we know that a body (earth) orbiting its host star (the sun) will move faster when it's close and slower when it's farther away. Otherwise the areas wouldn't be equal, and the law wouldn't be valid. Thus, the change in times of sunrises and sunsets are farther apart in January simply because the earth is moving fastest in its orbit. Kepler figured this out in part with Tycho Brahe by observing the orbit of Mars, which is more elliptical than earth's and so easier to note the effect and not attribute it to data noise."
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7mfvz6 | How do sacrificial zinc anodes work to prevent corrosion of other metals, such as a boat hull/motor in salt water? | Chemistry | explainlikeimfive | {
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"The specific type of corrosion that these anodes prevent is called [Galvanic Corrosion]( URL_0 ). Galvanic corrosion occurs when you have two dissimilar metals in contact with each other in an electrolyte (like water). The anode metal \"steals\" electrons from the cathode metal. This weakens and eventually dissolves the anode metal, causing the corrosion. A sacrificial anode, like Zinc, will very readily give up its electrons. Because of this, any electrons will be stolen from the Zinc (which is easy to replace) instead of some other metal (like steel beams).",
"Ahoy, matey! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: What are zinc anodes, what do they do, and how do they work? ]( URL_2 ) ^(_10 comments_) 1. [ELI5. How does a sacrificial anode work? ]( URL_4 ) ^(_3 comments_) 1. [ELI5: Why are sacrificial anodes not used on cars? ]( URL_1 ) ^(_4 comments_) 1. [ELI5: how does saltwater cathodic protection cause corrosion to only affect the zink and not the steel? ]( URL_0 ) ^(_8 comments_) 1. [ELI5: How/Why does Cathodic Protection work? ]( URL_3 ) ^(_3 comments_)"
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7mge1v | Why does frost sometimes form this way on the inside of my windshield? | Chemistry | explainlikeimfive | {
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"text": [
"There are tiny scratches in your windshield there. That forms the basis of nucleation sites for water vapor to freeze first. Nucleation is the hard part of freezing. Scratches make it easier."
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7mglm5 | Why does produce from farmer’s markets cost more than organic produce from a grocery store if the middlemen are removed? | Other | explainlikeimfive | {
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"In countries like the USA (where labor is costly), farmer's market stands are not cost-efficient. You have a whole person or two, putting in 4-6 hours of work, just to sell a couple of hundred dollars worth of produce.",
"Produce from a real farmer's market is likely from a small, local farm. A lot of the organic produce at grocery stores [still comes from giant corporate factory farms]( URL_0 ) just like the conventional produce, they just follow the USDA organic regulations. However you should still check that the farmer's market is a certified producer-only market. Otherwise it may actually just be [the same produce as the grocery store]( URL_1 ) (bought from the same wholesalers) with a higher markup at a kitschy stand."
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"http://www.tampabay.com/projects/2016/food/farm-to-fable/farmers-markets/"
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7mh8cl | The process of turning milk into bones | My understanding is that milk (and other dairy) contains calcium which our bones need, but the body can't use it without D3 which it creates by going out in the sun. When you drink milk does the calcium build up in your system waiting for you to get some D3? Or does D3 sit in your system waiting for calcium? What happens between the calcium and D3 to turn it into bones? | Biology | explainlikeimfive | {
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"Milk doesn't actually help build bones. As u/yellowyeti14 mentioned, milk actually hurts bone growth. The idea that milk improves bone growth was a very successful marketing ploy that sounds feasible because it has a reasonable amount of calcium and calcium is useful for bone growth. This however isn't the whole story. The whole story is that the lactose and casein in milk are acid forming once digested, and since calcium is a base, most of the calcium bonds to the formed acid and is neutralized. Additionally, there is usually more acid formed than calcium consumed, so your body actually starts pulling calcium away from its bones to neutralize excess acid. If you want to build strong bones, eat green leafy vegetables.",
"Milk contains various building blocks for the body, and as you've pointed out calcium is one of them. Vitamin D is important in creating bones, but it is in your body anyway, assuming you don't live in perpetual darkness. Yes, children who grow up in dark environments but with ample food typically have lower bone density, but at the same time it's not the key ingredient. Bodily processes are incredibly complicated, and the process of ossification (making bone) is not as simple as calcium+vitD=bone. There are thousands (that we know of) factors that directly or indirectly affect bone development and repair. Vitamin D and calcium are just a part of the whole equation, and lacking either of them is rarely the cause for problems with bone development. In fact, it's rarely spoken about, but one of the most important roles of calcium in your body is to do with how cells \"stick\" to one another - through little anchors that require calcium to properly work. ~~This is why calcium deficiency is more obvious in places like the mouth (scurvy) - where the cells in your gums literally fall apart from one another because of the junctions I mentioned earlier.~~ Calcium and Vit D are important for bone growth, but the equation is much broader than that. Neither waits for the other, and unless you are *severely* malnourished, they won't be the thing that affects the growth of your bones. You get plenty of calcium from the food you eat and the water you drink (especially if you live in an area with \"hard\" water, which is heavy in ions like calcium) Further, milk isn't there to provide calcium - it's more of a side effect. Many foods like citrus ~~(hence I mentioned scurvy earlier)~~, cereals, seeds, and fish have a higher content of calcium in the same volume as milk. Milk has a lot of fat and protein which is much more important to the body than the tiny amounts of calcium it needs Edit: I mixed up Vit C and Calcium in the scurvy point",
"You don't really turn milk into bones. Bones are made of a combination of a protein called collagen and calcium phosphate. So eating/drinking more calcium and protein (which milk has both) allows your body to make more bone. Think of construction workers building a wall. The wall are your bones and the workers are your bodies processes that mske bone. If you supply the workers with more brick and material they will be able to build a stronger, thicker or taller wall. Similarly if you give your body more calcium and protein (particularly while you're still growing), it will be able to make stronger bones. Vitamin D (which is also in milk) helps your body absorb the calcium you eat, otherwise you will just pee it out."
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7mhgs5 | As stupid as it sounds, why can’t the US keep selling bonds and increasing the national debt? | Economics | explainlikeimfive | {
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"This is exactly what we are doing all the time. How are you thinking this is different...?",
"If people were willing to buy the new bonds, then they absolutely could. In fact, that's exactly what happens every year - many old bonds are paid back with the money gained from issuing new bonds. The entire concept of government debt through bonds is a gamble: people buy bonds because they're confident that they'll be paid back when the bond matures. If that confidence disappears, nobody will buy new bonds, and the government will have a debt crisis. For most countries, this is a very safe gamble. Strong governments are a very safe place to invest your cash. The USA, for example, has never missed a payment, *ever*. So people are quite confident in US bonds, and the US would have to go *waayy* farther into debt than it is now for people to lose that confidence.",
"Absolutely nothing stops the US from doing this, other than the willingness of people to buy the bonds. At the moment and for the near-term foreseeable future, US treasuries are the safest inflation hedge available on the market and demand is gangbusters, so the US has absolutely no problem financing its debt by selling more of it. There's nothing 'illegal' about it, it's 100% the willingness of people to buy the bonds that allows the US to sell them at rock bottom interest rates."
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7mhsiy | Why does a good pair of headphones/earphones make it feel like the sound is coming from inside the middle of your head? | Edit: RIP Inbox... I knew thee well... Edit 2: Front Page! Wow! | Technology | explainlikeimfive | {
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"To put it simply, whenever a sound comes out of both the left and right channels at an equal volume, your brain will often trick you into believing that the sound is coming from the midpoint between the two channels, creating what's known as a Phantom Center. And since the left and right channels are on either sides of your head, your brain will have you believe that the sound is coming from the middle of your head. Here's a link if you're interested in a slightly more detailed explanation: URL_0",
"A good pair of headphones *doesn't* make it feel like the sound is coming from the middle of your head. A good pair of headphones makes it feel like the sound originates from well outside of your head, with a good soundstage.",
"They don't. GOOD headphones try to reproduce the neutral sound of flat speakers as best as possible, including making it sound like the audio is coming from around you rather than inside your head.",
"It depends a lot on the recording technique, actually. Your brain uses a number of queues to determine where sound comes from. The most obvious is that sound is louder in the ear closest to the sound source. It also arrives sooner to that ear. Less obviously, the external part of the ear changes the frequency spectrum of the sound, emphasizing high (treble) or low (bass) content depending on the angle the sound approaches from. For sounds produced externally from the ear, the brain is **great** at figuring out where they're coming from. What this means is even if sound isn't recorded in a way that intentionally gives the impression of coming from one direction or another, you'll still be able to tell the location of the speaker that's playing it for example. Only headphones (especially in-ear headphones) can bypass all these systems and deprive your brain of the info it needs to understand the source of a sound. But for it to sound like it's coming from inside your head the audio engineers need to have NOT done any tricks to make it sound like it's coming from some other location... which can be as simple as an instrument being louder in one ear than the other. So lots of audio won't sound perfectly centered. The microphone or a number of other items/effects may create frequency content differences that may give the impression of direction (or at least an external source) as well, even if it wasn't intended by the audio engineer.",
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: When wearing headphones, why do you hear the sound inside the head, but if you uncover one ear you hear it right in the covered one? ]( URL_1 ) ^(_2 comments_) 1. [ELI5: When I listen to some songs in headphones and can 'feel/hear' different parts of the music in different places inside my head, how does this happen? ]( URL_0 ) ^(_8 comments_)",
"3d sound effects. Plays right sound in right speaker then softer in left with a delay. You know to trick your ears into thinking it came from in your head. Could make it sound like from anywhere, really, with this tech. Same way you can hear where a person is walking in counter strike relative to your position and facing. Ray kurzweil reverse engineered the hearing center of your brain and printed it on sound cards then was able to figure out how it worked. So today we have software surround sound. When steam was brand new you had to get an expensive sound card to get 3d sound. Back in the day you couldnt tell if someoen was in feont of you or behind you above you or below you unless you moved your head and got 2 sound points to figure it out. Pretty sweet eh? An actual application of aetificial intellligence from reverse engineering a part of the human brain. And it made him rich.",
"Can someone expand these explanations to further explain how binaural sound recordings work? Ya know, where your brain can tell exactly *where* it was recorded (360 degrees, i.e. lower back left vs upper front right). [Example. Cool part starts at around 2:30.]( URL_0 )",
"Why is this post upvoted so much? ***SHITTY*** headphones make it feel like the sound is coming from the middle of your head, actual **GOOD** headphones make it feel like the sound is *around* your head. If you think Beats studios, Skullcandy extra bass headphones, or Bose noise-cancelling headphones are actual good pairs of headphones, then you have my condolences.",
"There's a lot of opinions here about the definition of \"good headphones\", but I think the answer you're looking for is this. A good pair of headphone or earphones is designed in a way that will, to the manufacturer's standard, accurately reproduce the source material. This is primarily based on two parts. The first is componentry. Shit parts = shit results. The second is processing, and physical design. Phase alignment between bands (low < - > mid, mid < - > high, low < - > high) is easily one of the biggest things to get right, and a manufacturer that's taken that into consideration and executed it in the correct fashion is likely going to have an excellent headphone.",
"Music is made to sound like this. It is called the [Haas Effect]( URL_0 ). By creating a very quick echo, the music can sound like it is coming from anywhere in the room of the artist's choosing, including in your head. The Haas Effect is popular in pop music because it sounds similar to singing along with a song, feeling as if you're there singing with the musician.",
"Sound waves from speakers don't just enter your ear through your ear canal, but rather they interact with your chest, skull, the shape of your ears, even with hair covering your ears. The ways in which sound is filtered by your own body before it reaches the ear drum is what allows you to hear the space around you. This is how your brain expects to hear on a constant basis, but headphones more or less inject the sound straight down your ear canals. Music is produced first and foremost for speakers. The overwhelming majority of music is produced in a way that means there's no spatial information in the audio that's useful to headphone users beyond your simple left-right pan. Most studio recordings have a single mono microphone on a single instrument or vocalist in an acoustically controlled environment (minimal reverberation). The mixing engineer then produces a mix that sounds good on speakers, but it's often said speakers *play the room*. They reflect and reverberate around the environment they're producing sound in to create a deeper sound field. Headphones simply don't do this; they are *acoustically dry*, with no contribution from room acoustics. The very best headphones do a better job of fooling your brain into thinking the sound they produce is coming from a three dimensional space, they have some tricks like using a larger driver for the sound to come from a larger area, and using drivers that are set at an angle relative to your ears (both of which should result in a sound that involves reflections of the outer ear more), but this doesn't guarantee a spatially accurate sound. FWIW I've also heard it said what audiophiles call \"soundstage,\" or the out-of-head presentation headphone users are looking for, I've heard acoustic engineers simply refer to as \"accurate treble response\" (the reasons I've discussed above also make this very difficult to achieve; i.e. your accurate treble response might not be the same as someone else's due to physiological differences.) Even the best headphones, to this day, fail to produce as realistic a soundstage as even 2 channel stereo speakers."
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7mj1d0 | what is the difference between the cheap batteries that come in toys and major brand batteries, like Duracell, and why does the latter last a lot longer? | Technology | explainlikeimfive | {
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"Usually toys come with an \"extra heavy duty\" battery which is a generic name for [zinc-chloride]( URL_2 ). These batteries are really bad. An AA might hold 1.5 watt-hours of power. Some really cheap toys come with \"heavy duty\" batteries or zinc-carbon. These are the worst and an AA might have 1 watt-hour of power. Duracell is an [alkaline]( URL_0 ) battery. An AA might hold 3 watt-hours of power. Twice or three times as much! But there is an even better battery out there. The [NiMH]( URL_1 ) battery doesn't hold any more power than an alkaline but it will never leak inside your stuff. And it is rechargeable so it can be used over and over. Saves a lot of money that way. To avoid a lot of fancy mumbo jumbo let's just say that NiMH can also \"push\" electricity a lot harder than alkalines can so they do better in toys with motors or flashlights or stuff like that.",
"The cells in the nicer batteries are more energy dense, that is also why they tend to be heavier assuming you are using like for like alkaline vs alkaline, lithium vs lithium. This density is measured via how many milliamp hours a battery has."
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7mjaib | How come touch screens only work when they come in contact with skin and not other things? | Technology | explainlikeimfive | {
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"Most touch screen sense the increase in capacitance when something conductive gets very close to the screen. Metal or conductive rubber can also affect touch screens. Edit: Capacitance is a property of capacitors. Capacitors are made of two conductors separated by some insulating material. The screen has two independent transparent layers of horizontal and vertical lines. A finger adds to the capacitance on the lines. The position is determined by measuring the capacitance and finding the lines with the highest values.",
"Touch screens these days mostly work on detecting changes to electrical properties. You are conductive and touching the screen changes electrical properties that your phone is measuring. Your phone then knows where you touched. Oh forgot to mention that the screen has tons of small invisible wires for you are making contact with. Things like gloves are insulators and don't change the electrical field because it doesn't interact with electricity. So your phone can't detect it."
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7mjngx | Why is a slow resting heart rate good, when it is also healthy for your heart to beat fast during exercise? | EDIT: So several answers have come in, but I'm not sure my question is being understood. I'm asking, if it's healthy for your heart to beat fast during exercise, why isn't it healthy for it to beat fast(er) during rest? Wouldn't a higher resting heart rate almost be like a mini "workout?" Making it stronger? | Biology | explainlikeimfive | {
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"its about strength and efficiency. Your question is quite valid... Why can't we just do Cocaine or drink caffeine to increase our heart rate for \"exercise\"? Or just be panicked (increasing our heart rate) to get a good workout? It takes a little knowledge to come to a good conclusion. Ahem. There's an upper and lower limit to your heartrate. Everyone's different depending on age and health. We've established some \"normal\" ranges. About +- 70-85 BPM at rest is normal; then the top number is dependent on some factors that you can look up on your own. Anywho, the heart is a muscle (duh) right, and it's activated and regulated by the bodys need for it's service (pumping blood). During stress it increases it's rhythm for both psychological (anticipation), and physical (sustaining, survival) need. More on this in a min. So depending on how your health is, the body prefers a sorta calm state; (feelsgoodman.exe), your average resting heart rate lies in this realm. Anything above this indicates *some* sort of stress on the body. There's healthy stress and unhealthy stress. Unhealthy stress includes: unnecessary psychological anxiety/fear, drug use, sickness. While good heart stresses are things that lead to better states like: exercise to \"look better\" or strength to protect yourself, or even light activity like getting some food from the store (food endorphins bruh). Regardless of what you do, your body is reacting in harmony with what will sustain you. So it's like just because your HR is high or low doesn't mean it's good for what you're after. Like a higher BPM is normal in sick people but your body is battling something which is good but if you lay around sick for months your muscles waste away because of lack of use . The body is always changing according to automatic (unconscious) and consious need. Understanding the hearts basic role then leads us to better answer your questions. You **gain** something from the **right** high heart stresses which are reflected in your heart rate. Consistent exercise (along with healthy eating and habit) nets gains both physically and mentally \"look good feel good\" (dopamine bruh). The bodies equal reaction to being well all around is a lower HR at rest when calm. There's plenty more to look up about heart health that's awesome. You can get a baseline of your health with your sleep HR vs resting HR vs exercise HR vs rebound to resting HR after exercise, this is almost a sure way to indicate overall health. Hope this was helpful.",
"The heart is a muscle, and it needs regular workouts to build its strength. The two things you ask about are strongly correlated. If you get regular, extended aerobic exercise where your heart beats at its maximum sustained rate (~ 220-age) then it will grow strong and at rest it will be able to beat at a low rate and still circulate your blood.",
"To answer your edit: It is okay for your heart to pump fast during exercise because exercise is a short duration and while you're exercising, the heart is strengthening. The reason it is not okay for your heart to pump fast during rest is because you rest for a majority of your life. 1/24 of your day may be exercising but the other 23/24 is normally resting. Your heart should not be beating that hard for 23 hours a day. It will not be able to have sufficient rest and wear your heart out at a much faster rate."
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7mjoo2 | When a train enters a tunnel, what is the cause of the sudden pressure drop in the cabin? | I was riding CalTrain today and in the 4 tunnels before the final stop there was a quite noticable pressure change (which I found to be a drop in pressure using the barometer on my phone). Thank you! Rule 7: In accordance with rule 7, I did search this question up beforehand, and there were two posts about the topic, but one of the posts described an increase in pressure (which I found not to be the case) and the other didn't have that great of an explanation. | Physics | explainlikeimfive | {
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"When air speeds up its pressure drops. As the train passes through the tunnel the air around the sides is being squeezed into a much tighter space than before the train’s presence. A narrowing of the space between the train and the tunnel causes the air to speed up which also means the pressure of the air drops as it speeds up; speed being relative in that it’s the train that’s moving while the air is still but the effect is the same."
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7mjrb8 | Exactly How is snow depth measured? | Erie has 60 inches but watching the news it looked like only a foot maybe foot and a half of snow. Where’d they get the number 60 inches? | Other | explainlikeimfive | {
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"At a weather station there is a plate and ruler used to measure the snowfall. The snow is measured and once a certain amount builds up on the plate, it's cleared to accurately measure new snow. The snow that isn't regularly cleared compacts so there's less than 60\" inches of standing snow everywhere else. After the snow has fallen, sun can cause some of it to begin to melt (further compacting it) so there will usually be much less snow sitting anywhere than the measured amount that fell."
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7mjt6b | Why do humans and other animals go unconscious when severely injured? | Biology | explainlikeimfive | {
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"The exact reasons of course depend on the type of injury. A disruption to circulation means insufficient oxygen to the brain. Damage to the brain itself may interfere with the mechanism of consciousness itself. I assume, however, you mean passing out from pain. I believe there is some suggestion that, as your body has to work against gravity to get oxygenated blood to the brain, and the brain is an extremely hungry consumer of oxygen, falling down decreases the work your body has to do to continue to oxygenate the brain. While obviously being unconscious poses a significant risk in many circumstances, if your body could not otherwise successfully oxygenate the brain (Say due to some severe trauma) then it doesn't matter if you stay conscious anyway, because you're toast. So it may at least provide some possible advantage over not passing out.",
"Usually because they’re losing a lot of blood. Less blood = less blood to the brain = less oxygen to the brain = brain goes unconscious. In other cases, it’s the same reason that some people faint when they see blood: it’s a reflex. Your body says: “Oh no, I’m bleeding/going to bleed to death” and tried to compensate by lowering your blood pressure (which means less blood flow which means less blood loss) rapidly which usually causes you to faint. Seeing blood triggers this reflex in some people.",
"The brain takes up a lot of energy, shutting it down can give the body a better chance to recover. Also, in the case of blood loss, there might not be enough oxygen in the blood to keep the brain going at full power. And various brain injuries can prevent the brain from operating properly for a short time."
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7mjyr9 | why does Netflix (and other videos) get stuck at “99%” buffering? Shouldn’t the percentage accuracy display the time left? | To add on: it will steadily increase from 0-99 at a fairly constant rate, but stay stuck at 99 for like 25s. This is inaccurate, but why does this happen? Why is the algorithm not able to incorporate that wait time and distribute it across the buffer timer, so that once it hits 99 it doesn’t wait, but instead the video resumes? | Technology | explainlikeimfive | {
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"\"loading screens\" are notorious for their prime purpose is to placate the user that something is happening, and not for being accurate or honest. Unless the people who coded Netflix's loading % function come in here and tell us how it works, you can assume its either right or wrong but we have absolutely no way to actually tell what is happening behind the scenes. This is one of the dirty secrets of software loading... sometimes, its just bullshit, sometimes it isn't, its hard to tell.",
"So it loads extra time. It's not honest, but the last percent is giving it extra time to load more of the video. Except the part of the code to load more says don't load too far, using more internet for netflix. This means it gets stuck between loading quickly whats right up next and slowly what's a few seconds away. It takes much longer to stop buffering than it does to refresh the page. The same thing happens on youtube for a different reason. You can be loading from where there's no loading space left (past the light gray bar) and it'll take much longer than dragging it back a bit and playing it.",
"The way coding works, loading bars are sort of like you sending a text (responsibly, when stopped) on the way home from work to keep your partner updated on your ETA. You get to a red light, text your significant other that you're now at X point in your journey and that Google Maps is saying you're X minutes away--then you carry on driving. & nbsp; Continuing that analogy, you can only accurately say how far you've gone and when you'll arrive home *based off of the assumption* that the environment doesn't change . . . realistically, no one can accurately predict when they will get home 100% of the time--no matter where in their journey you ask them to give you a status update. & nbsp; Back to Netflix's loading bar: the program says \"98% of all the code needed to run is done, put it up on the loading bar!\" It's most likely giving you an accurate assessment of the % of loading that it's completed as well as % left to load. & nbsp; However, that last 2% could see network issues (like you could end up behind an accident) or something failing (like you could end up IN an accident). If something like that occurs, then there you are, just like a significant other who texts back, \"It's been almost half an hour since you said you were 2 miles away!\" & nbsp; And that's also why most programs, especially those reliant on network availability / access, decline to give the end user it's best guess for how long it will take to get from A to B. In the end, it just wouldn't be useful or accurate."
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7mk4o2 | What’s the difference between a statue and a sculpture? | Other | explainlikeimfive | {
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"A statue would be a specific form of sculpture. Generally they depict the full form of a person or other animal in a free-standing form. A sculpture in general would be some form of three dimensional art."
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7mk5hp | Why are almost all products showcased on tv, cheaply made and usually not worth the money? | It seems like every product that proudly displays the 'As Seen on TV' tag is usually nothing but empty promises and cheaply made. I've never seen a product that's been all over every channel that is genuinely worth the money asked. Why aren't more quality products actually showcased on tv? Wouldn't these channels want to show products that are actually worth the money? Don't these poor products actually hurt the overall reputation of the producers that give them the air time? | Other | explainlikeimfive | {
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"> Wouldn't these channels want to show products that are actually worth the money? No. People who choose to watch 30 minute infomercials aren't at a good place in their life. They're frequently dealing with insomnia. People who want to research a product go to amazon, or the store. > Don't these poor products actually hurt the overall reputation of the producers that give them the air time? I think people are happy with their purchases. I think that a huge percentage of the buyers are elderly, or disabled people who don't get out much and who find the experience of learning about a product on TV, talking to a phone rep, and getting it to be fun.",
"Late night, afternoon, just after prime time, the TV station *has* to fill airtime. So someone with some cheapass junk, buys airtime and sells the merch. They empty their warehouse, the TV station doesn't have dead air at that timeslot and a viewer has a lighter wallet. Keep in mind that viewership at late night on a station with no network shows drops. Of those who tune through, *someone* is going to buy that piece of plastic crap."
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7mk7bt | Why is ice slippery? | Physics | explainlikeimfive | {
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"When a flat ice surface comes into contact with another surface it typically melts and forms a layer of it's own lubricant (water). This lubricating layer actually separates the ice from the surface it is contacting slightly which significantly reduces friction. You see a similar but more pronounced effect when you put a piece of dry ice on a flat metal surface. The contact with the metal surface sublimates the dry ice into gaseous CO2 at a high rate creating a gas layer that inhibits contact (and thus friction) between the dry ice and the surface. The more pressure is applied the more CO2 is sublimated and a low friction layer is maintained. The same is true for water ice. More heat and pressure liberates more liquid water to lubricate and seperate whatever the ice is in contact with. Interestingly, ice that is below melting does not have a low coefficient of friction with itself or other cold things. Rubbing two very cold pieces of ice together creates a feeling of friction similar to smooth rock or glass. This is because the cold ice on cold ice does not create the lubricating boundary of water which would otherwise reduce it's friction."
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7mka8z | Why does toilet paper get wrinkly as you near the end of the roll? | Other | explainlikeimfive | {
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"Didn’t work with toilet paper but when I worked at a factory (think tape and other assorted things) I worked on a winder line. Sometimes when the rolls were not tightened on all the way (without getting into too much detail) they would wrinkle, but depending on what type of adhesive the tp manufacturer uses it could just be that the tp folded over. Hope this helps!"
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7mki9b | How do we not fall over while walking and standing on just two legs? | Biology | explainlikeimfive | {
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"r/answers, because you've learned how to balance yourself. Minor shifts in the muscles in your feet shift your weight to keep balance. Arms can act as counterbalances to the movement. Watch a toddler that's still learning to walk, they fall over all the time. People who have suffered major injuries often need training to re-learn to balance themselves.",
"Just like we have smell, tact, or sight, we have the [sense of balance]( URL_0 ). There's three main factors coordinating our balance: (a) what our eyes see, (b) the liquid inside the channel of our inner ear, (c) and the perception of ourselves in the space. For the first one, sight, I recommend to check this video beforehand: [\"Moving walls\" experiment at the Institute for Sport, Physical Education and Health Sciences, Unive]( URL_2 ). In short, they have people standing still in a room with moveable walls, when the walls are still, people keep their balance, when the walls move, people lose their balance. For the second one, there's liquid inside the [vestibule in the inner ear]( URL_1 ). In the vestibule there's cells that are sensitive to pressure, the liquid is usually \"down\" because gravity is pulling it, therefore, the cells in the bottom part of the vestibule are being told \"this is down\" by the pressure of the liquid. If you've ever spinned fast and suddenly stopped, you've surely experienced momentary dizziness. That's because the liquid hasn't quite settled down, so, the cells in the vestibule are sending signals all over the place to your brain. Finally, for the third one, perception of ourselves, it's a mix between the last two and the muscles. When we're young and are learning to move in space, we're training our muscles about how far and fast we can move, which way is up, which one is down, etc. That gives information to the brain about our surroundings, leading to an understanding of your position in space and how you can interact with it. It's even possible to keep balance if you lack one of the first two. For the first one, sight, imagine a blind person, they don't have the visual feedback but they aren't falling down all the time. For the second one, vestibular system, imagine astronauts in space, there isn't any gravity pulling the liquid but they aren't dizzy all the time. For the last one is kinda hard because it's almost impossible to take away the muscles. That's why we don't fall after learning to stand and walk, our body and brain have signals from our surroundings and from inside telling us which way is down and how we're moving relative to the space."
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7mkk9j | How does mouthwash work, and why does it foam up in your mouth? | Chemistry | explainlikeimfive | {
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"Mouthwash is mainly an antiseptic. In most cases it is alcohol based but this is not essential. Mouthwash foams because the companies that make it add a foaming agent. A foaming agent is added because market research says that people prefer cleaning products that foam up."
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7mknod | Why is some fat yellow and some fat white? | I just had some Christmas sausage and noticed the fat deposits in it are white. The fat on a ribeye steak is also white. But when I dissected a frog in high school, the fat was yellow. Why are they different colors? | Biology | explainlikeimfive | {
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"Chlorophyll is the molecule that makes leaves green. It is important in photosynthesis, which allows plants to absorb energy from the sun. Carotene is the molecule that makes plants yellowish-orange. It helps transfer the energy from chlorophyll. The green chlorophyll usually overpowers the orange color carotene, but you can see the carotene in the fall when the leaves change color. You can also see it in carrots, squash, pumpkins and other vegetables. Beta-carotene is a type of carotene that is very important for humans and animals. It's converted to the colorless vitamin A. Some animals store the yellow/orange carotene in fat cells, which makes the fat look yellow. Some animals tend to store the colorless vitamin A in fat cells instead, which keeps the fat cells looking white. Chickens tend to have yellow fat. Cows tend to have white fat. Cows that eat a lot of grass tend to have more yellow fat. Cows that eat mostly grains tend to have white fat. Ironically, many people think yellow fat in meat is disgusting, even though it is a hallmark of grass fed beef, which is considered a higher end product. As a final fun fact, beta-carotene is the reason why butter is yellow."
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7mkyqs | In the movie The Social Network, how exactly did Eduardo get screwed out of the company when he signed the new contract after Facebook was re-incorporated | Economics | explainlikeimfive | {
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"Pretty much all major companies in the US are based out of Delaware. Facebook wasn't. So they created a new Facebook in Delaware that would then purchase the existing Facebook. Eduardo signed the papers without reading them very closely or getting his own lawyers to look them over. He thought it was just a small bureaucratic headache, trusted Mark, and thought the lawyers worked for him. But really, the documents gave Mark the right to issue new shares as he saw fit (which is also necessary in a growing company). Mark gave those newly created shares to himself and all the other investors, but not to Eduardo. This diluted Eduardo's shares. It was a long time before he noticed."
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7ml4da | What happens when singing along to a recording or in the shower that affects our perception of our own voice compared to singing by ourselves | Other | explainlikeimfive | {
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"Singing with a recording will fill in tones and notes you miss, which feels satisfying on your brain. -AReal Brainscientist"
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7mldo6 | What is Chaos Theory? | Mathematics | explainlikeimfive | {
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"Chaos is \"when the present determines the future, but the approximate present does not approximately determine the future.\" In other words, chaotic systems have no actual randomness - knowing the current state would tell you everything you need to know to determine the future state - but in practice they're unpredictable. They're so sensitive to the initial conditions that having a very good approximation to the the initial conditions doesn't help you to predict a good approximation of the future. A tiny change in your measurements quickly compounds into a huge difference in the predictions."
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7mlpkd | Why do trainers cut the boxer's near the eye or sometimes called bloodletting ? | Other | explainlikeimfive | {
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"When they get hit in the eye hard enough it causes swelling. The swelling can in turn reduce the boxers ability to see. By making the cut it allows blood to escape the sore and helps alleviate the swelling.",
"This happened to me once. When I was in high school I did backyard wrestling with some friends. One day I got elbowed in the eye really hard and my eye was swollen shut. My mom pulled out her knife and gave me a quick little poke. Five minutes later I was back in fighting shape."
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7mlq72 | Why does cancer come back? I have heard about the threat of cancer returning from people who have been cured, but if the cancer is fully removed how can it come back? | Biology | explainlikeimfive | {
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"Cancer like any disease has a threshold or detection number, below that number it goes unnoticed, or cured. The disease has no ill effects at this level. It may still be there but we don't see or feel it. Like being wet, a single drop on your clothing may not be noticed, and you would say \"I'm dry\"; but a oz, a qt, a gallon will be noticed and at a certain threshold you will say \"I'm wet\".",
"You do not get cured from cancer, cancer can only be treated and suppressed, but the moment tumor growth is more than 1mm in size, it becomes hypoxic, which leads to angiogenesis of new leaky blood vessels through which depraved of oxygen tumor cells can spread in an epidemiological attempt to look for new places in the body to survive, in other words - metastasis. Those metastasized cells will remain dormant in satellite organs, like lungs, bone marrow, liver, or may start growing right away. So someone who has had a successful chemo and cancer was gotten rid of, it’s just a matter of time before metastasized tumor cells come out of the dormancy and start growing into new tumors. This is why after initial cancer, one needs a major lifestyle change like different correct diet, a lot of exercise, antioxidant foods, no red meat, no burnt meat etc. this would postpone and prolong the remission period. Cancer is never fully removed, initial original tumor may be completely removed, but metastasis has begun long before the tumor has been detected in most people’s cases."
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7mm2ry | Why is it when some wounds heal, they leave a shiny scar, whereas others leave dark patches of skin? | Does it have to do with the size, type or depth of the injury? How to reduce the size or colour of the scar? | Biology | explainlikeimfive | {
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"It deals with how that particular injury heals. Your skin is multilayered. The very top layers are actually dead. Underneath are the living tissues, softer, \"normal skin\" layers closer to the surface and \"basal\" layers below. These basal layers are slightly different from the ones closer to the surface and when you are injured, they play a role in 'filling the gap'. In small, superficial wounds, everything heals up to 'normal'. But not all the time. Sometimes the wound closes with those basal layers comprising most of the 'new' skin.",
"Probably depth of injury and whether or not it bleeds. If the wound is mostly superficial and doesn't pool with blood, the scar tends to be shiny. If it bleeds, or the scrape is deep and the wound is open for a while, it tends to be dark and most often raised. Source: Experience. I got loads. Both accidental and otherwise."
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7mmaj8 | Why do road cyclists try to eliminate friction if it is needed to move forward? | Edit:Tire friction | Physics | explainlikeimfive | {
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"You want friction between the tire and the road (i.e. traction) but not friction within the tire itself (rolling resistance). Tires deform as they roll and this process takes energy. Wider tires with taller sidewalls have greater traction, but high rolling resistance and will slow down the bike. For a road bicycle, the weight and the speed involved doesn't require all that much traction to give good control. That allows tire design to minimize rolling resistance and wheel weight instead.",
"Friction of your wheels on the ground helps you move forward. Friction of the wind on you body slows you down. What friction reducing measures do you mean?"
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7mml5v | How does Lead Poison recovery work, and why and how do people 'feel worse before they feel better' if they are removed from the source of the lead problem? | Biology | explainlikeimfive | {
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"Did you ask your physician these questions? I’d suggest calling their office if your husband is having additional symptoms or problems. They can give you information on what to expect and, considering they know how he was poisoned and what his levels are, problems to watch out for.",
"Yea, you should probably talk to your doctors again. I'm not an expert of course, but here is what i know... Lead is really really not good for our bodies. It bonds strongly to bones, teeth, hair and nails, which basically keeps it in our systems. For enzymes, it can mimic other metals (zinc, iron, calcum, etc), to disrupt the function of enzymatic processes... processes which generally run the entire body. It can create radicals (compounds/elements with just 1 electron) who reacts with other living systems. It interferes with DNA transcription and reduce vitamin production. All this can lead to the production of inflammatory cytokines; an over reaction by the immune system. Its pretty much a complete system shock, depending on how much (40um /dL is pretty high). As a result, the areas affected, and the symptoms produced are wide-ranging. Where ever that Lead end up in his body will be a difficult thing to remove, just due to the chemistry of the atoms. Those symptoms are potentially correct for what has occurred. *What I want to know is what to expect as his blood/lead decreases* His system is an a functional deficit. He will probably have a lot of physiological responses, depending on where the doctors found the affected areas, and how it was ingested. The stomach, GI tract, cardiovascular system, and brain are usually affected; he will have mental instabilities (like lethargy, anxiety), GI pains, and tightening (myalgia)... it seems right, but i am not a doctor or lab worker who knows him. As the lead begins to be removed from the system, he will have reduced symptoms. This will occur once the cellular turn-over rates have elapsed. There may be residual lead in peripheral areas leading to slow exposure, and so he may have these symptoms randomly again; leads half life in our bodies is about 30 years, if i recall correctly. Your time-line should be a slow descent into \"worseness\" then a gradual incline into restored function, due to this turn-over rate. *What is 'worse before better' broken down?* The \"worse-before-better\" is the system needing to completely recover a LOT of critical units. You can imagine it as if his body didnt have these organic functional units for the duration of his poisoning. The body needs to break down strongly-bound proteins, and rewire a buttload of pathways who were affected. The high doses of Vit C help move the reaction from new enzymes favoring Lead to Vit C (and other, natural, salts). It also needs to successfully make these enzymes and DNA without interference, which is dependent on the diluted volume of lead. *I am confused and do not know how to help! He is on a multivitamin and anti anxiety medication presently.* Yes, it will be a painful recovery. Lead affects so much of our organic system, that all you can do is be attentive to symptoms your doctor told you to watch out for. Those which fall out of the range may be a concern. The mutlivitamin and V.C treatment will make things better from the sounds of it, so you just need patience and vigilance. Hope that helped."
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7mmqrm | When did WASD become the standard for movement control in games and how did it become so widespread across all games? | Technology | explainlikeimfive | {
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"It was some dude that played Quake. I'll see if I can find an official source, but some people had been using WASD but this guy was the first famous player to do so. [Source]( URL_0 )",
"it evolved from the very first first person shooters. back then in the days of wolfenstein and quake, lots of movement layouts were popular. wadx, esdf and szxc. wasd became popular at the top level gamers so everyone wanted to be like the pro's",
"I've always used ESDF and only ever recall seeing one game about 20 years ago come with ESDF as the default. Don't remember the name though. I find it better because your fingers are on the home row keys for typing and there's more keys around your hand to bind stuff. Great for MMOs. For shooters my pinky rests on A for crouch. Try it",
"It became common in the mid-late 90s when 3D shooters like *DOOM* started to take off on PC. Early games often used the arrow keys, but their placement on the keyboard makes it very difficult to use any other keys. As games got faster and more complicated, enthusiasts realized that mapping movement to wasd gave you access to many more keys that could be mapped to other actions and was a more natural sitting position. Within a few years it became the industry standard."
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7mmweq | How is it that deadly/debilitating allergies such as peanut allergies were able to persist in our DNA? | How is it that a deadly/debilitating allergies were able to survive in our DNA for thousands of years, wouldn't the carriers of such a huge flaw in our DNA have died of long ago? | Biology | explainlikeimfive | {
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"It's only been about 1,000 years since the majority of humans could even come into contact with peanuts, let alone afford to eat them. Peanuts need a warm wet climate I believe, so the British would have little ability to grow them and the expense you would go through to ship it from a warm wet place back to England basically meant that only the king could afford it. Thus you have a huge population that never needed to be immune. You see this with lactose as well, European descendants are generally fine with lactose because they cultivated milk and cheese, where as many African cultures did not use milk beyond infancy, so African descendants are much more likely to be lactose intolerant. Long story short, lack of international commerce let us keep food allergies.",
"Allergies aren't purely genetic, and have a significant environmental factor as well. This means that where the environmental factors are absent, the genetic factors can spread without notice and the allergy will only manifest when the environmental factors later present themselves. Imagine, for example, you had a mutated gene that would kill you if you ever saw the the letter X. If you grew up in a place where you never saw the letter X you would be able to pass that gene on to your offspring."
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7mn3sg | Moon moving away... but gravity? | I know the Moon is moving away from the Earth at a slow rate 35 mm a year I believe? But how is that possible with the Earths massive gravity? Thanks in advance. | Physics | explainlikeimfive | {
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"the earth spins faster than the moon orbits, so imagine a ball on a rope you are holding while you spin. it moves outwards as you spin faster and inwards as you slow down. the moon slowly pulls on the earth, slowing our rate of spin, slowing in turn the rate of its escape. eventually it would've slowed the earths spin so much that it matched its orbital velocity at which point the earth and moon would be locked in tidal orbits where only one face of the earth could see the moon. but the sun will destroy us and it before it has the chance to wind up in that scenario",
"It's a combination of two things. The first is tides. The Moon's gravity pulls on Earth and causes it to be not quite spherical: Earth develops \"bulges\" that point toward and away from the Moon. When you're standing on a bulging part of Earth, it's high tide; when you're standing elsewhere it's low tide. The second thing is Earth's rotation. The fact that Earth is constantly spinning doesn't play well with the fact that Earth has bulges in line with the Moon. It means that the bulges are constantly rotating out from underneath the Moon, instead of staying in line. So a force appears: the Moon pulls the bulges backward a little bit, slowing the Earth's rotation, and the bulges pull the Moon forward a bit, speeding up its orbit, in an attempt to keep the bulges in line under the Moon. Eventually, given enough time, Earth's rotation will slow down enough, and the Moon's orbit speed up enough, that the two will be equal. One Earth rotation will equal one Lunar orbit, so the bulges will stay perfectly lined up. This is called *tidal locking*. What does this have to do with your question? Well, it means that the Moon is speeding up slightly in its orbit. And one of the laws of orbital physics says that a faster orbit moves you farther away. So as the Moon speeds up, it drifts away from Earth slightly."
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7mn403 | Why do USB cables have a max length? | title | Technology | explainlikeimfive | {
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"When designing a protocol like USB, there are some parameters that need to be set. Depending on how you want to handle collisions, acknowledgements, retransmissions, ... you have to choose different parameters, including cable length. The USB engineers figured their protocol was going to be used to connect PC devices in an office setting. Therefore they found it appropriate to limit cable length to 5m, in order to allow a cable delay (= time a signal needs to travel through the cable) of 26ns. [Source]( URL_0 )",
"The longer a cable is, the more electrical resistance it has. USB ports only put out so much power, so if the cable gets too long, the signal gets too weak to be read.",
"As cable length increases, so does its capacitance. This tends to 'round off' the square waves used to transmit digital signals. That makes it harder (less reliable) for the receiver to discriminate where the waves (bits) begin and end, leading to data errors.",
"To ensure they work reliably The longer your cable, the more noise it will pick up and the more the signal will lose power. The cable length standards are set so that in a normal environment, a cable of that length will work reliably. If you are in a super noisy environment or have a bad cable then it may misbehave before then, if you're in a low noise environment you may be fine with a longer cable; but the point is to provide a max length guideline for a normal environment.",
"(this turned out longer than I expected) Imagine a garden hose that's passing through some rough terrain (think: lots of thorns and other sharp things). Inevitably, some of these thorns will puncture small holes on the hose that leak - in fact, let's say you can be certain that, for every 10cm of the hose, there's going to be, on average, one small hole. Each of these holes means less and less water is getting to the end of the hose and there's inevitably going to be a point where you have too many holes and not enough water is reaching the end. Because we have one hole per 10cm on average, this means that the longer your hose, the less water gets to the end of it. Of course, you can just use a better material - if you make a higher-quality hose, there will be less holes and thus you can have it longer without losing as much water - perhaps a different (more expensive!) material will sustain more thorns, so the holes appear every 30cm rather than 10cm. Still, there's always going to be a limit in length, where too much water is leaked and the hose is useless. Now, back to the subject of USB: while imagining cables to work like garden hoses is an oversimplification, we can certainly draw an analogy in that the longer your cable is, the weaker the signal is (due to background noise, resistance and other factors). To make longer cables that actually work, you need to use more expensive materials. And, keep in mind that, when it comes to cables, a broken cable may still work under some circumstances - when I say broken, it usually means \"flaky\", i.e. a good cable always works - a bad cable sometimes, under some circumstances, doesn't. Finally, imagine you're the organisation that needs to come up with the USB standard. Specifically, you want to make sure bad cables (as defined above) are easy to spot. One option would be to only manufacture cables yourself. Nobody else is allowed to make USB cables and problem solved. Another option is to demand that any company that wants to manufacture cables needs to send you a sample to review. Neither of these scale well, of course. So here's a third option: find the shittiest, cheapest material that can be used to build cables and assume all cables will be like this. This works well both when the standard is in an early stage (you make pessimistic decisions when you come up with how it works) and to set limits, like the cable length, knowing that, even if built from the worst possible material, it would still work reasonably well, as long as it's less than 5m."
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7mn4bw | Why does running cold water sound different from running hot water? | Physics | explainlikeimfive | {
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"The differences in density and viscosity are the causes. Cold water will have a higher pitch due to the stronger surface tension and hot water will have a lower pitch due to the weaker surface tension breaking up the water before it hits the glass or whatever you may be pouring it into. That's why coffee or something warm will have a low sound and a cold glass of water will sound higher."
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7mn9l4 | Probability using cards | Mathematics | explainlikeimfive | {
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"[Wolfram can speed up the math on this, but your odds of getting 3 out of 10 is just 0.26%]( URL_0 ) Since it is an infinite deck of cards then every draw has equal probability and you don't need to worry about combinations equations and can just use P(x)=p^x * (1-p)^n-x where \"x\" is the number of yellow cards(3 or 1 in your examples), \"n\" is the number of draws(10 or 100) and \"p\" is the probability of a yellow card (3%) This equation is the result of taking all your draws and saying \"what are the odds i succeed 3 times (p^3 ) what are the odds i fail the remaining times (1-p)^(10-3) and you get your result",
"This is an example of a binomial random variable. Basically, there are some number (n) events (draws) that occur with a fixed probability (p) of being a \"success\" (yellow card). The probability of getting x \"successes\" is: n!/(x!(n!-x!))*p^x * (1-p)^(n-x) The logic is, more or less, the probability of getting 3 \"successes\" out of 10 when p=0.03 is 0.03^3 * 0.03^7 (the probability of getting 3 \"successes\" and 7 \"failures\" all in a row). However, since there are multiple different ways to get this combination of events (three yellows right away, 2 yellows then a non-yellow, then another yellow, etc..) we have to account for each possible way. That's what the part with the factorials out front represents, all the possible ways to pick three things from ten things. There are plenty of [online calculators]( URL_0 ) out there that will do the math for you if you give it the parameters it needs. In this case the probability of getting three yellows in 10 picks is 0.00262."
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7mnedg | Why is it easier to wake up when you actually want/need to do something? | Biology | explainlikeimfive | {
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"Sleep is controlled by serotonin, acetylcholine and noradrenaline amongst others. In this case, when you need to do something you have higher noradrenaline levels (sympathetic drive) and this causes you to be more awake. It's not to do with dopamine, as others have posted! Source: neuroscience student"
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7mnfrr | What's the point of letting people plead guilty or innocent before a trial? Wouldn't it always be better to plead innocent and hope that you get lucky during the trial? | Other | explainlikeimfive | {
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"Well, sometimes a person really is guilty and doesn't contest the matter. Also, defending yourself is not free. Lawyers are expensive. Additionally, pleading guilty can lead to a more lenient sentence. Pleading innocent when you're very likely to lose is a costly endeavor.",
"Doing justice fairly is time consuming and expensive. In some cases the prosecutor and police are able to convince the person accused , the defendant, that they are absolutely going to lose at trial. In those cases the prosecutor can go to the defendant and say \"hey, you know we'll prove that you did it. So how about this, if you agree to plead guilty, and forgo the cost and time of a trial, we'll reduce your punishment slightly.\" The defendant likes this deal, because he knows the evidence is stacked against him. Better to spend 5 years in prison, instead of 20 right? The prosecutor likes this, because it means they can spend more time on other cases.",
"A person who pleads innocent does not have a chance to make a plea bargain - they are taking their chance that the jury will find them innocent of the crime and not sentence them as charged. The person has an idea of what the MAXIMUM possible sentence is if they are found guilty, but they do not know what the jury/judge will give them if they are found guilty. On the other hand, oftentimes, a suspect's defense lawyer and the prosecuting attorney can come to an agreement on a \"plea bargain\" (agreement of conviction or punishment terms) if the suspect agrees to plea guilty - this saves time and resources in the legal system. It is a way of letting a person confess to a crime, show remorse, and understand EXACTLY what they are going to be punished with beforehand. For instance, a person who was caught with 1 kg of cocaine while driving their friend's car could face ... say $15,000 fine and 8 years in prison for drug trafficking charges. If the person pleads innocent (with the defense that \"it was my friend's car, I didn't know\"), they go to trial, and if they are found innocent, they don't have to do anything, but if they are found guilty they could face the maximum penalty. If they work out a plea bargain, it's possible they might not have to pay a fine at all, and they might only have to do a few years in prison with the remainder of the time being served on probation. They have that guarantee and know what to expect."
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7mnkig | In what ways are doctors and nurse practitioners similar and in what ways are they different? | Other | explainlikeimfive | {
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"Nurse practitioners often have years of nursing experience and then return to get their masters degree and become a medical provider. Some work under a Physician guidance but some can work on their own. Physician assistants are similar to nurse practitioners in that they have clinic experience, get their masters and become a provider. Currently, however, physician assistants must work under a physician’s guidance. Both nurse practitioners and physician assistants are called mid-level providers that can diagnose, treat, prescribe, order imaging, office procedures, and surgeries. All things a doctor can do but under the supervision of the doctor who has more education. Mid-level providers were created to help with the lack of medical care available. The population is growing rapidly and there aren’t enough doctors to care for everyone. Mid levels can see patients and then consult with the doctor if needed or treatment doctor just looks at the notes at the end of the day.",
"My wife is a doctor so maybe I have a bias here. She went through 4 years of medical school. The last 2 years of med school are performed in the field. She is in the first year of a 4 year residency program for ob-gyn. Residents are expected to work 80 hour weeks in what amounts to an apprenticeship. When she finishes residency she will have 20,000 hours of experience beyond classroom. A nurse practitioner has a masters degree that can be done in 2 semesters. Then they need 6 months of apprenticeship. They end training with about 1,000 hours of experience. NP is cheaper but you get what you pay for. Edit: formatting"
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7mnn71 | How come in aquariums the predators don’t gobble up the prey? Are they trained not to do so? | Biology | explainlikeimfive | {
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"Many fish will only attack when they are hungry, or won't attack fish they the don't recognize as food. A good aquarium will be curated to take both these into account, and will only contain well fed, mutually compatible species.",
"In large enough tanks, where there is a large variety of species, they sometimes do. But generally otherwise, if they're well fed, it doesn't happen too often.",
"A well fed fish is less likely to eat other fish. However, this isn't always the case and many predator type fish will in fact go after anything they can fit in their mouth. When stocking predator aquariums you do have to be careful to stock compatible tank mates, otherwise, you risk other fish/shrimp becoming a meal. Lionfish, eels, groupers are examples of saltwater fish where this applies and I've seen cichlids in freshwater eat tank mates as well.",
"When my students (3rd grade) asked the docent this question he asked them, “What vegetable will you never eat?” “Broccoli!” they shouted. “Well, these fish are like broccoli to the eel. He thinks they taste yucky and will never eat them.”",
"Predators are evolved to get their required calories as efficiently as possible. Given the choice between the tasty, pre-killed meal the keepers give them whenever they are hungry and a live, healthy fish that can easily swim away and hide, the smart shark will take the easy meal. To that end, you could say that the predators are \"trained\" to only eat dead food.",
"It is rare for aquariums to put predatory fish in with their prey species. For the extreme predators they will be in an isolated take by themselves, sometimes down to a single tank for a single individual.",
"The predators DO gobble up the prey in aquariums. Most aquariums are just mindful to keep those fish in separate tanks.",
"I've toured a few large aquariums and done some of their behind the scenes things, and most of them have a very specific system of feeding for each animal in the tanks, I believe it was Seaworld in Orlando where I saw they have charts for each animal (mostly sharks in this tank with some other smaller fish), and will put their specific food on a big pole and wait until that shark circles by, and will feed it. Then it gets recorded on the chart so the sharks are never hungry enough to go after the smaller fish. They did say very occasionally sometimes a shark will eat a display fish, but it's not very common because of their system.",
"It actually also depends on the fish. It’s kind of like how you can have a dog at home that happily lives with your edible pets (rabbits, for example). The predator will always be capable of snapping and eating the prey, but whether or not they do it at that particular moment depends on how hungry they are, if the prey starts to flee and makes them chase, the predators actual temperament, etc etc. It also depends on the size difference. Fish generally won’t try to eat something that isn’t sufficiently small. Anecdote: My in laws have an Oscar (intelligent, carnivorous fish) which has its own pet feeder fish. It actually chews up its fish food and spits it for other fish to eat. It’s had them in its tank for about 8 months now - and they were put in there for it to eat, it just likes having them I guess.",
"Dunno if it happens at all aquariums, but there are some that separate the predators from the prey with glass. Big fish will try to get at the little fish and fail every time. Eventually, behaviorism will kick in and the big fish won't try again, even if there's no glass. Then, they intermingle them as they like.",
"Actually had a conversation about this with the owners of a diving center with all kinds of fish. They introduce the prey fish first, so they can start looking for hiding places, long before predators are added. They also played different sounds for different kind of feeding times, so they are trained to only group together when it's their time to eat. If the fish would all be fed together, some smaller fish would definitely disappear...",
"I worked in an aquarium for almost 5 years. The larger predators are usually kept so fat by the staff that they have no interest in eating anything extra. It's like during a holiday when you stuff your face with all the tasty food and then when someone mentions desert you panic and realize that you didn't leave room for desert! So you decide that you'll wait until a little later to have a tasty snack. Sometimes you have that snack later on - when no one's looking - and other times you pass because you're still too full. For sharks in a community tank with hundreds of other fish who are being hand fed by humans several times a day, there's no need to have a snack. Every day is a holiday when you're an aquarium shark! That being said, sometimes a shark may indulge themselves and have desert despite being full. As an aquarium employee you can only hope that they do it when no one's looking!"
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7mnrp4 | Why do horses bob their head when walking? | They bob their head when walking but when they go faster (trot, canter, gallop) their heads stay still. Why? | Biology | explainlikeimfive | {
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"Its called the balancing gesture, the weighty head and neck are balancing against the hindquarters to keep the whole body balanced. a horse uses a balancing gesture at every gait except the trot/pace. They dont at the trot because front and back legs are working in unison, there is no back to front balance. Your statement that there is no balancing gesture in canter/gallop is incorrect."
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7mns1g | How does siphoning gas from one car to another work? | Other | explainlikeimfive | {
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"Once you get enough suction to make a gas bridge through the hose, gravity causes the gas to \"fall\" the rest of the way into the other car's tank. Usually people will use a canister instead of their car if their car's tank is higher than the victim's car tank.",
"To begin with your sucking pulls the liquid down the pipe along with gravity as the destination container will be below the source container. When the liquid is moving through the pipe something must come in behind it to fill the vacuum. So long as there is only the liquid to fill the vacuum then it will keep drawing the liquid down the pipe.",
"These answers are correct but modern vehicles have an anti siphon device that won't allow a hose into the tank. You can get a mouthful of gas but it will not hold prime. I know this from personal experience.",
"You put a long tube into one tank, start sucking and once you've got the petrol coming you lower the top of the tube so that gravity takes care of the rest. Pour into a can, pour the can into other car. Don't get any in your mouth (this is the hard part)"
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7mnx99 | Why do humans have so much potential for gaining strength (Olympic weight lifters can lift almost 9x what the average person can), but the difference between the average runner and Usain Bolt is only 2x? | Biology | explainlikeimfive | {
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"There is a big difference between those 2 things: One requires more muscle mass. More muscle mass can generate more force. When you lift a weight you can slowly activate more muscles fibres contraction generating more and more force until it is enough to start lifting the object. Running on the other hand is a very complex movement. You constantly change multiple different muscles between contraction and relaxation. And there is an upper limit how fast you can do this, as this requires actual chemical processes (besides the bio-electrical processes from neurons firing signals) within the muscles to achieve the contraction and relaxation processes in constant exchange. There are different muscles that can do those processes faster, and you can also train them to a certain degree on a bio-electrical and chemical level to do those actions faster, but at some point you reach the chemical limit for the muscles to do that action.",
"In simple ELI5 terms. Humans are already optimized to run, so the average person is a lot closer to the maximum. Humans are not optimized to lift heavy objects, so the average person isnt naturally built to do so, an thus when you optimize a person for that, they have a lot farther to go.",
"To refine your examples just a little... There are no Olympic weightlifters that squat 1200lbs. There have been only a handful of powerlifters who have ever squatted over 1200, wearing multi-ply lifting suits. Olympic weightlifting does not compete the squat. Olympic lifters routinely squat 2-3.5x their bodyweight in training, with the heaviest in common knowledge at almost 800lbs. Smaller lifters have a proportionately higher ceiling on their strength. The world record squat for a 123lb lifter is more than 5x, but the 308lb class record is just under 3x. This trend is mirrored in relative speed among different size animals, as well. The fastest animal on Earth is the Tiger Beetle, running almost 125 body lengths per second. They’re so fast they go functionally blind while in motion. I guess that opens a whole new list of interesting questions.",
"Air resistance can be a big factor. It might help to use the example of a bicycle as I know the numbers involved with that. The best cyclists can sprint at 70kmh and they require around 2,000 watts of power to travel at that speed. An average untrained person should probably be able to do at least half that speed, 35kmh but at that speed they only need 250 watts. That's about 8 times the power required to travel at twice the speed. On a bicycle at least, doubling the power of the rider will usually lead to an increase in speed of only around 30%. In the case of Usain Bolt, while he may be running twice as fast as an untrained runner he would be producing far more than twice the amount of power with most of that power going towards overcoming air resistance. Researchers calculated that Usain produced up to 2,619 watts at the 2009 world championships with 92% of that power overcoming drag. ( URL_0 )",
"Well just looking at it from a math point of view. E=0.5m*v^2 Mass is directly proportional to the energy needed. So a doubling of mass is a doubling of energy, however a doubling in speed quadruples the amount of energy. I'm sure there's some body mechanics that inhibit faster running too, such as our short feet compared to faster animals.",
"Lifting has a singular requirement, sprinting has two competing requirements. Speed, human or otherwise, comes down to power to weight ratio. A great runner can develop a lot of power while simultaneously be relatively light weight overall. Adding power may not pay off if it adds additional weight. A power lifter has no requirement to keep his weight down, it is all just a matter of how much power he can supply, how muscular he can become. He may add all the power he can without a downside that added weight would bring to a runner.",
"I think you're coming at it from an incorrect premise. First, lets get the terminology out of the way. No weightlifters are squating 500kg+. You're talking about powerlifters. Second, the current world record back squat is 1268lb (575kg) and was lifted by a person with a body weight of 308lbs (140kg) while wearing assistance gear. Whereas the raw (no assistance gear) back squat world record is only 1052lbs (477.5kg) but was lifted by a person who weighed upwards of 360lbs. Your average 360lb male can easily squat 130lbs, and could probably squat at least their body weight with minimal practice/training.",
"You're not comparing equivalent things here If i get you a random untrained person off the street they can probably squat 130 once If i get you an untrained person off the street i doubt they could hit a 6 minute mile pace even for 100 meters. That's a pretty good pace for a well trained runner, while 135 pound squats is a relatively low weight for someone who squats regularly. You've compared a novice to an olympic weight lifter and a well trained runner to an olympic sprinter. You should either compare well trained and well trained, or novice and novice If you pick someone off the street who isn't into running you're probably talking closer to a 10 minute mile(~6 mph) which puts Usain Bolt at about 4.6x faster. That's a lot closer Energy consumption vs speed isn't linear for running, that's likely where the remaining factor of 2 is hiding",
"Remember there's a massive difference in geared vs raw lifts. URL_0 Also, look at it in terms of steroids. Speed athletes need to balance power/weight ratio as well as fast twice vs slow twitch muscle fibers and spending time developing vo2 max. Heavy lifters are only concerned with powers. Steroids are way more effective in developing raw power than endurance. So the difference is 5/2 rather than 9/2",
"All of these answers aren't actually answering OP's question. The real answer to this question is math and how min-max ranges are perceived when compared without context. This is no different than those skewed bar graphs that show a range of 0-1000 next to another one that is 0-100, the numbers on the x1000 chart will look teeny tiny compared to the x100. Same thing here. It's not 9x or 2x anything, it's the difference in units you are amazed by, not the value. When a person can run between 0-30mph, that is going to seem way less significant than weight lifting which is on a scale of 0-1,000+. You aren't seeing those numbers in context relative to each other, you are just looking at large numbers vs small numbers on the same level without context to what you are actually measuring. Edit: Here is what I'm talking about URL_0 Same values, skewed ranges",
"Once mature, you can make your muscles thicker, but you cannot make them longer. Maximal strength is limited by muscle thickness and maximal velocity is limited by muscle length.",
"Think of your muscles like a computer. You can overclock a computer and make it a little faster. You can even add liquid cooling and go faster still. But you pretty quickly hit a speed limit. There is nothing stopping you from buying more computers, however. With more computers you can spread your workload across them (much the way a modern supercomputer works). Eventually you do run into limits (whether it's power, or cooling, or the ability to split up your workload)- but those limits are much higher than simply trying to make a single computer faster. Muscles are similar. In terms of speed- we can train muscles to be a little faster and we can improve our running technique which will also help- but we hit a limit pretty quickly. Strength, however, has more to do with more muscle fibers and spreading the load across them (just like with more computers). When people strength train- their muscles get larger (more fibers) and thus can lift heavier objects. Just like with computers there is a limit to the number of muscle fibers you can fit, as well as limits to the strength of our skeleton and the muscle attachments- but those limits are much higher than the limits for how fast a muscle can react."
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7mo3w7 | Why does coffee tear up my stomach, but espresso drinks sit just fine? | Biology | explainlikeimfive | {
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"I cant explain with science, but my guess is that the acidity in coffee is agitating your mucosal lining. Although espresso may seem \"stronger\", I don't believe the acidity is significantly higher than milder coffee beans to account for the differences in quantity. For example, your latte may have 2 or 3 shots (ounces), but a small coffee at a coffee shop is usually 12 ounces. Congrats on being able to tolerate milk though!",
"There is a lot of milk in a latte. If you o it put a few tablespoons in a regular cup of coffee then that would make sense."
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7mo4mw | If a person were larger than average, wouldn’t they be able to take a higher dosage than the recommended suggested? Shouldn’t they have to? IE 3 ibuprofens instead of recommend 2. Or 2 glasses of red wine instead of 1. | Biology | explainlikeimfive | {
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"Yes. Specific medicine dosages are by body mass. 2 pills is for average people. Andre the Giant would not be taking the same amount of Tylenol as Verne Troyer",
"the labeling on the sides of OTC drugs are for an \"average\" person. if you're not an \"average\" person then consult your doctor for special instructions. one \"drink\" has been standardized as 12oz of beer 5% ABV, 5oz of wine 12.5% ABV or 1 oz of liquor 40% ABV. there are charts showing the BAC of weight and number of drinks. this chart is not accurate and is only a guideline."
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7moadg | How does bone conduction headphones work? | Physics | explainlikeimfive | {
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"Yer not alone in askin', and kind strangers have explained: 1. [ELI5:Bone Conducting Headphones ]( URL_5 ) ^(_4 comments_) 1. [ELI5:How do bone conduction headphones compare to air conduction headphones in terms of safety? ]( URL_2 ) ^(_3 comments_) 1. [Has anyone used Bone Conduction Headphones? ]( URL_0 ) ^(_12 comments_) 1. [Thoughts on \"bone conduction\" headphones? ]( URL_3 ) ^(_12 comments_) 1. [Bone-conduction headphones for hard-of-hearing people? ]( URL_1 ) ^(_._) 1. [ELI5: Do bone conduction headphones work on people that are deaf? ]( URL_6 ) ^(_3 comments_) 1. [Bone conducting headphones ]( URL_4 ) ^(_11 comments_)"
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"https://www.reddit.com/r/headphones/comments/68u0lq/has_anyone_used_bone_conduction_headphones/",
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"https://www.reddit.com/r/explainlikeimfive/comments/6i5ytj/eli5how_do_bone_conduction_headphones_compare_to/",
"https://www.reddit.com/r/headphones/comments/4rt3hk/thoughts_on_bone_conduction_headphones/",
"https://www.reddit.com/r/headphones/comments/4t5zrr/bone_conducting_headphones/",
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7mojfo | Why did most of the mammals from the Ice Age go extinct? | Biology | explainlikeimfive | {
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"text": [
"The Pleistocene overkill hypothesis suggests that the time frame of the extinction of Pleistocene vertebrates matches the spread of humans through North America. Although this theory is mostly based on North American human expansion it could possibly be correlated to the rest of the worlds situation as well.",
"It got warmer, and so species better adapted to warmer flourished and those adapted to the Ice Age conditions died off. It's no big deal or conspiracy, climate change has life-threatening impacts on creatures that don't have spaceships and other planets to move to."
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7momim | If some medicines suppress symptoms of a cold, and if having symptoms usually align with someone being contagious, do cold medicines briefly make someone less contagious? | Biology | explainlikeimfive | {
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"Not really. They can make you cough and sneeze less, and produce less mucus. This limits how contagious you are. But because of how the medicines treat the symptoms, you probably won't stay at home in bed. This makes you more contagious as you are in contact with more people."
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7morzj | Why do the high and low temperatures for the day rarely reflect actual temperature? | I live in the Pacific Northwest and today it says High 46, low 45, currently 37. This happens a lot. Why does the forecast look like that? | Other | explainlikeimfive | {
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"In some regions the forecast is very accurate. Where it is not, there are two main reasons: 1. Microclimate. The temperature is forecast for a specific location, such as downtown or the airport. A few miles away, due to mountains or bodies of water, the weather may work differently. 2. Lack of data. Most weather systems move from west to east, and most weather monitoring stations are on the ground. So forecasters on the west coast are at a disadvantage, with no cities far west of them."
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7mp1yj | Why does holding your breath, or refusing to exhale when you stub your toe, or kick the coffee table temporarily reduce the pain you feel? | Biology | explainlikeimfive | {
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"text": [
"It increases your blood pressure and sensors in your lungs blood vessels dampen your central nervous system (which takes messages from your body to the brain) and so reduces pain sensitivity."
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7mp2gj | White hole space curvature | If white holes do or were to exist, spewing out energy and mass at a rate where you can not approach them. Does that mean, in the common simplification of "the rubber sheet", these objects would raise the sheet up? And if so; are there other, real or theoretical, objects that do this? | Physics | explainlikeimfive | {
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"I don't know a lot about white holes, but they are gravitationally attractive like black holes, not repulsive. In fact, they are so similar to black holes that it is not clear that they are really different things at all. The one measurable thing that distinguishes white holes is that they emit particles - but when you add quantum mechanics, black holes emit particles too (Hawking radiation). Curved rubber sheets, as a model/analogy for gravity, are unrelated to curved spacetime. The equations [1] describing the motion of massive particles on a horizontal rubber sheet in a uniform gravitational field happen to be almost the same as the equations of *Newtonian* gravity, if you make some idealizing assumptions. Pictures of curved space in general relativity look similar to pictures of bent rubber sheets, but it is coincidence. In general relativity, only the intrinsic shape of spacetime matters. If you turn a bent piece of general-relativistic spacetime \"upside down\", it makes no difference, because its intrinsic shape is the same. If you turn a rubber-sheet-analogy surface upside down (preserving the shape, so it's not really rubber any more...), it turns gravity into antigravity. & nbsp; [1] (namely F = -∇Φ and [Poisson's equation]( URL_0 ) ∇^(2)Φ = 4πρ, where Φ is the Newtonian gravitational potential or the altitude of the rubber sheet)"
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7mp2wz | How birth defects happen | How do these actually become decided, and why do they happen? | Biology | explainlikeimfive | {
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"There are many causes and many different situations. Some defects are chemically triggered, a perfectly normal fetus exposed to thalidomide at the wrong point in its development will turn out with a defect. Some defects are genetic, through a copying error or expression of a recessive trait a fetus will develop with a defect. The concept of \"decide\" and \"happen\" carry the connotation of understanding and thoughtful decision making that doesn't make much sense in these biologic processes."
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7mpc12 | How does GPU/CPU bottleneck work? | First of all, I’m truly sorry if this has been asked here before, im new here on reddit and i couldn’t find an answer. So, what is exactly that “phenomenon”? What makes it happen? I’ve heard a lot about it and I’ve seen explanations for it but I truly need an ELI5 for this one. Thank you all in advance and sorry for any misspelling. (I’m Portuguese) | Technology | explainlikeimfive | {
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"A \"bottleneck\" in a system occurs when a single part of the system limits the performance of the whole system. Every system has a bottleneck or critical step, the goal is to make sure its as well balanced as possible so you don't lose too much performance In terms of CPU/GPU bottlenecks, it is when one of the two is more heavily loaded than the other. Certain games load up the GPU heavily, and others load up the CPU heavily If you're playing a Shooter game with graphics cranked up to max then your CPU might be finishing the math it needs to do for each frame in just 2 ms, there isn't much work it needs to do. Then it hands it off to the GPU that needs to start drawing, but you have AA cranked up super high so the GPU has to do a lot more work and it takes 15 ms to get the frame ready. When its done the CPU already gave it the info it needed for the next frame so you get the next one 15 ms after. This gives you just 66 FPS despite the CPU being able to do 500 FPS. In this case, the GPU is the bottleneck If you're playing a strategy game, which is traditionally more CPU heavy, then the CPU may take 20 ms to complete its calculations for the next frame before handing them off to the GPU. The graphics are reasonable so the GPU does its math and spits the frame out 2 ms later. This restricts you to just 50 FPS despite the GPU having plenty of spare processing time. In this case, the CPU is the bottleneck which leaves you with an underutilized GPU. There's always a bottleneck, the goal is to identify it, make sure its where you want it, and minimize it.",
"Imagine you have a big bowl of M & Ms in front of you, you take a handful, and put them into your mouth. You take a second handful, but your mouth is still full, so your hands have to wait until your mouth is finished with the M & Ms it's currently working on, before it can take any more. The same with the next handful, and the one after that. It's the same with a bottleneck in a PC, one part, either the CPU or GPU can't get through the work quick enough, so the other part has to slow down to do work at the same speed.",
"A \"bottleneck\" is just a way of saying that one aspect of a system is the primary limiting factor. Imagine trying to dump out a bottle of water - the mouth of the bottle is the part that slows down everything. Some games do a lot of complex things on the CPU, like AI, physics, tracking hundreds of moving objects in the game world, etc. This work can't be unloaded onto the GPU so, if the CPU is working at full capacity, it's considered the bottleneck even if the GPU would be capable of running things faster. Some games do a lot of complex things on the GPU - having high resolution graphics with complex lighting and amazing textures. This work can't effectively be done by the CPU so, once you've hit 100% of the GPU's capacity, that's the bottleneck in your system."
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7mpw3q | How can causation be distinguished from correlation? | Other | explainlikeimfive | {
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"Reproducibility in isolated experiments by independent actors. Causation is stated to be the case when experiments can be held affirming the hypothesis - for example, the temperature going below 0 C is strongly correlated with ice appearing in nature, but once you isolate all other factors and have people put cups of water in their freezers and observe the water freezing, you can say more or less for sure that cold temperatures cause ice to freeze. There is a line of philosophical thought that wholly rejects empiricism and rejects the idea of causation entirely, though."
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7mpxir | What are moles in chemistry? | I have struggled with this question since high school. I just can't grasp it. I don't know why. I dropped chemistry in college because I couldn't get it. Please dumb it down to me. Really, explain like I'm two. I need someone to explain it to me. What is mole? Why are we multiplying this random number? Why is it needed? | Chemistry | explainlikeimfive | {
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"A mole is simply 6.02 x 10^23 of anything. Molecules. Beer cans. People. Candy bars. It is like saying 'a pound'. It is just a numeric measurement. Its usefulness is chemistry is that for each element, if you have the Atomic Weight of the element in grams, you have that many atoms of that element. Written out, the number is roughly 602,000,000,000,000,000,000,000",
"A mole is just a number of atoms - specifically the same number of particles found in 12.000 grams of carbon-12. In general, a mole of an atom will have a mass in grams (very nearly) equal to its molecular weight - a mole of gold (atomic weight of 79) will weight 79 grams. Let's say you want to take a bunch of Hydrogen & Oxygen and then make water out of them. How much of each gas do you need to make sure you have enough atoms that everything reacts together without extras? If you take 1 mole of each, you know that you've got a balanced chemical reaction.",
"It's needed because we picked the weight of the gram by tying it to a specific volume of water. Well, water isn't an element and the volume we chose was big enough that a whole bunch of water molecules fit in it. Alas, the number of water molecules that fit in that volume isn't a nice round number **and** water isn't a very good place to start the scale as a lot of things are lighter than water. Oops, we need a conversion constant. It turns out that the constant, called the [Avogadro constant]( URL_0 ), is 6.022140857(74)×10^23 elemental atoms per mole. With this constant, one mole of hydrogen atoms weighs one gram. Hydrogen is the lightest element, so that's a great thing to have weigh \"1\".",
"> What is a mole? You know how a dozen is 12? A mole is (roughly) 6.02×10^23 , same idea. A dozen of eggs is 12 eggs. A dozen of roses is 12 roses. A mole of oxygen is 6.02×10^23 oxygen moleclues. A mole of gluclose is 6.02×10^23 gluclose molecules. > Why are we multiplying by this random number? Having studied high school chemistry, you seldom multiply by avagadro's constant in chemistry except in test questions like \"how many atom of oxygen is X moles/grams of oxygen?\" > Why is it needed? Because we are dealing with a huge number of atoms/molecules in real life. Imagine you sell oranges, and for packing or whatever reasons, your supplier sells you oranges in boxes of 98. Now, you won't say \"I want to order 294 oranges from you\". That would just be difficult for everyone. You say you order 3 boxes. Once you get used to that, you may refer to 49 oranges as \"0.5 boxes of orange\" even when you are not talking to your supplier. That is the same with moles. You don't want to say \"1.204×10^24 molecules of H₂ reacts with 6.02×10^23 molecules of O₂ to produce 1.204×10^24 molecules of H₂O\". You say \"2 moles of H₂ reacts with 1 mole of O₂ to produce 2 moles of H₂O\" Now since we know, from the periodic table, that 2 moles of hydrogen is 4.0 grams, 1 mole of oxygen is 16.0 grams, and 2 moles of water is 20.0 grams, (I hope I get this right. Been a while) we know how much hydrogen and oxygen to use if you want to produce water this way. In chemistry, we mostly measure stuff in grams and moles, and covert between them. This is becuase we can measure mass of something easily, and we know X moles of substance A reacts with Y moles of substance B from the reaction equation."
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7mpxz1 | Why do electronics need a certain voltage? Wouldn't current be what's important? | Wouldn't the flow of electrons be what's important for powering a gadget rather than the electric potential? | Physics | explainlikeimfive | {
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"Voltage is potential difference, think of it like water pressure. Its how hard it is pushing the current in. This is important because of all the resistances it needs to push that current across to do things. Like how high the water pressure needs to be for an apartment building. The more floors/faucets the higher the pressure needed. So the current is what is important, the voltage determines if the current is strong enough to make it all the way through the device."
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7mqzh2 | Why do lights seem to move or blink when looking at them from far distances? | Other | explainlikeimfive | {
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"Obstructions in your view such as water vapor, dust, heat, cause the lights to appear to flicker. I'm sure there are probably several other reasons as well.",
"Yarr! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why do lights flicker from a far distance (especially city lights)? ]( URL_5 ) ^(_5 comments_) 1. [ELI5:Why do some lights flicker in the distance while some don't? ]( URL_3 ) ^(_2 comments_) 1. [ELI5: why do lights twinkle at a distance? ]( URL_0 ) ^(_7 comments_) 1. [ELI5: Why lights twinkle from far away ]( URL_1 ) ^(_2 comments_) 1. [ELI5: why do lights seem to flicker when they are far away, but up close they do not? ]( URL_6 ) ^(_2 comments_) 1. [ELI5: Why do lights appear to twinkle when they are far away from where one is standing? ]( URL_2 ) ^(_3 comments_) 1. [ELI5: why do lights in the distance appear to shimmer or flicker, but those relatively close even a mile or two away appear as \"stable\" as those next to you? ]( URL_4 ) ^(_6 comments_) 1. [[ELI5] Why do lights \"twinkle\" when seen from far away? ]( URL_7 ) ^(_5 comments_)"
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"https://www.reddit.com/r/explainlikeimfive/comments/2yxpf9/eli5_why_do_lights_appear_to_twinkle_when_they/",
"https://www.reddit.com/r/explainlikeimfive/comments/31wvbk/eli5why_do_some_lights_flicker_in_the_distance/",
"https://www.reddit.com/r/explainlikeimfive/comments/388enq/eli5_why_do_lights_in_the_distance_appear_to/",
"https://www.reddit.com/r/explainlikeimfive/comments/7bqhw4/eli5_why_do_lights_flicker_from_a_far_distance/",
"https://www.reddit.com/r/explainlikeimfive/comments/3h4ivp/eli5_why_do_lights_seem_to_flicker_when_they_are/",
"https://www.reddit.com/r/explainlikeimfive/comments/6aibx4/eli5_why_do_lights_twinkle_when_seen_from_far_away/"
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7mr4xf | How come after eating a lot of sour lollies, it feels like your tongue/gums have been cut? | Chemistry | explainlikeimfive | {
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"text": [
"Sour is acidity. That's literally what sourness is measuring. Your tongue/gums haven't been cut so much as chemically burned a little bit. Though you might aggravate it by chewing on your tongue perhaps giving you more of a literal \"cut\". Think about how the same chemical effect is burning at your teeth, and brush your teeth after eating sour foods. But use some mouthwash first, so that you don't brush at very weakened teeth covered in acids.",
"A lot of very sweet and very sour foods and candies have citric or ascorbic acid (vitamin C) in them. Even if an acid is very weak, it will still wear away at your teeth and the tissues in your mouth if you leave it there long enough. For example, the citric acid content of pineapple is high enough that if you were to spend about 10-15 minutes snacking on some, you'd get the same cut feeling, or maybe a burning/raw sensation in your throat. (plus a raw pineapple has bromelain which is quite toxic but that's a different danger.)"
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7mr8yv | why do stocks that don't pay dividends hold value? | Economics | explainlikeimfive | {
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"drw2kg2"
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"text": [
"They still represent ownership of the company. They have value because, hypothetically, if somebody ever wanted to buy the company, they'd have to buy up all the shares of the stock."
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7mrfm1 | How would a country’s currency lose its value (partially or entirely)? | Economics | explainlikeimfive | {
"a_id": [
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"text": [
"People lose faith that the issuing government is good for it. Pretty much every currency you might handle is based on the shared idea that it has value. Some percentage of total currency in use is backed up with holding of other foreign currency or precious metals, but it is not 100% and often not even 10%. Unlike say 100 years ago, any particular note you may have in your wallet or in your bank account does not entitle you to trade it in for a set weight of gold or silver (or a set number of Dollars/Euros/Yen). It is not a \"Gold Certificate\" or \"Silver Certificate\", but a trade instrument based on faith and confidence in the particular currency issuer. As long as everyone has faith in the currency and goes about their day, everything is fine. That is, you assume your national government is a stable and reliable issuer and your currency will be worth about the same next week as it is today. However, if a large enough group of people no longer feel that the currency is good or going to be good in the near future, there will be a large scale attempt to transfer their currency into a different country's currency, move into precious metals, durable goods or otherwise abandon a particular currency and devaluation begins to occur. People worry that their national currency isn't going to be worth anything next week, so they start selling it on the cheap this week in the hope of getting some value before the system becomes further devalued. If the national bank can't check this in time and restore confidence/value, volatility can spread through the system and runaway inflation can occur, driving the value of any particular denomination of currency down dramatically. If many/most/all people feel a currency is unreliable due to high volatility, it essentially becomes worth nothing."
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7mrkta | why is grapefruit bad for diabetics? | Biology | explainlikeimfive | {
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"it’s not inherently “bad” grapefruit contains compounds which contribute to several drug interactions, but many diabetes meds do not have this problem. the only thing that otherwise could potentially be harmful is the sugar content, but in that sense it’s no different than other fruits..."
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7mrm48 | How do coins in a coin pusher always pile up on the edge but never fall off? | Physics | explainlikeimfive | {
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"text": [
"A friend of mine operates these games they pay out 30-50% depending on how they are adjusted. the main mode of adjustment is the side holes where money falls into and goes into the bottom of the machine (this is the oeprators profit) can be opened and closed to adjust the payout, if the hole is mostly closed they will pay out close to 50% of what they take in, if itss open they pay out around 30% there isnt much trick to how you put in the quaters are far as i know. also the angle of the lip will adjust the pay out as well.",
"There was a fantastic reply above, but one way to look at it is that you are pushing something into the middle of a pile. That pile will expand in all directions it can...forwards, to the left, and to the right. Only one of those three sides is positive for you. There are a ton of factors which will influence how much goes forwards and how much goes sideways. One of the things you mention is a a big stack on the tip...if they are weighted (perhaps with a prize) static friction makes them not want to move, due to the normal force. Plus any slight elevation on the lip or other design factors. They want them to pay out enough so that you keep playing (and make up for those of us who cheated the hell out of those machines as teenagers), but not actually lose money."
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7mrmaa | How is lithium produced in the sun/stars? | How do elements with odd proton numbers generally originate in the centers of stars? | Physics | explainlikeimfive | {
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"For the original stars in the Universe, there was only hydrogen and helium. When a star forms over time due to self-gravitation, the increased pressure will increase the temperature and around 7 million kelvins the star will start thermo-nuclear fusion. This process starts with Hydrogen \"burning\" (there is no burning involved, but this is the term. The particles actually fuse together when they collide at high speeds) which takes 4 protons and turns them into a Helium atom, 2 positrons, and 2 neutrinos. This takes place over a few steps in phase 1 of the proton-proton chain. In phase 2, the first step is a Helium-3 isotope (created in one of the steps from phase 1) fuses with a Helium atom and creates a Beryllium-7 isotope and a photon (light). Then an electron strikes the Beryllium-7 isotope and creates a Lithium atom and a neutrino. This is the second phase of the proton-proton chain and there is another step, but this is how you get to Lithium. For the Sun, since it is a second generation star, meaning it formed after the original stars went supernova, it actually was born with a small amount of Lithium and other elements heavier than helium (referred to as metals in astrophysics). So the Sun always had it and makes more every day, which in turn gives us heat and light! This process can continue all the way up into Nickel, which will decay back down to Iron (for second Gen stars that are massive enough {Our Sun is not massive enough}). Any element heavier than iron needs to be produced in a supernova explosion"
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7msr7p | Why is it that your body will let you pee yourself while sleeping as a kid, but as an adult it wakes you up? | Biology | explainlikeimfive | {
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"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5:Why are adults woken up automatically when they need to pee, while young children pee the bed? ]( URL_1 ) ^(_ > 100 comments_) 1. [ELI5:Why I don't wet the bed after dreaming of peeing at an older age, but I used to when I was a child? ]( URL_3 ) ^(_14 comments_) 1. [Why do children pee the bed, but not adults? ]( URL_6 ) ^(_3 comments_) 1. [ELI5: Why do children and seniors wet their beds but not really for adults? ]( URL_5 ) ^(_1 comment_) 1. [ELI5: When we were younger we all wet the bed, how does your body change into not wetting the bed? ]( URL_0 ) ^(_1 comment_) 1. [ELI5: Why do children wet their bed? ]( URL_4 ) ^(_11 comments_) 1. [ELI5: As a child I would wet the bed if I dreamt I was peeing, as an adult this does not happen, why is that? ]( URL_2 ) ^(_3 comments_)"
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"https://www.reddit.com/r/explainlikeimfive/comments/5xyuo1/eli5_why_do_children_and_seniors_wet_their_beds/",
"https://www.reddit.com/r/NoStupidQuestions/comments/74vay1/why_do_children_pee_the_bed_but_not_adults/"
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7msulo | Where is gravity coming from? Is it energy out of nowhere? | Physics | explainlikeimfive | {
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"Gravity is not actually energy or a force like we understand forces. Gravity is a property of matter where it curves spacetime. Look at a globe. The lines of longitude are all parallel, meaning that they transect the equator at 90 degrees. Now, on a flat plane, parallel lines never meet and stay the same distance from each other. But on a curved surface like a globe, lines of longitude eventually meet at the north and south poles. So while a two travelers may start out miles away from each other but traveling along lines of longitude in straight lines, they find themselves meeting at the north pole. From the traveler's perspective, they are being attracted to each other by some unknown force, even though they're traveling in straight lines along a curved surface. This is similar to gravity. Objects with mass curve spacetime, so it's not a flat plane, but a curved surface. This curvature causes objects traveling along it in straight lines to come together as if there is a force causing attraction between them. But that just describes movement though space. Even objects not moving appear to be attracted to each other because they're moving through time together. If I didn't do a very good job explaining this, maybe [Michael from Vsauce]( URL_0 ) can help using the same illustration."
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7msz71 | What's the difference between ibuprofen, acetaminophen and Naxproxen? | Other | explainlikeimfive | {
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"For those who are not in the US. Acetaminophen = Paracetamol",
"Yarr! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: The difference between ibuprofen, advil, and tylenol. ]( URL_0 ) ^(_ > 100 comments_) 1. [ELI5: The differences between aspirin, ibuprofen, and acetaminophen ]( URL_1 ) ^(_ > 100 comments_) 1. [ELI5: The difference between Advil, Tylenol, Motrin, Ibuprofen, Acetaminophen, Aleve, Aspirin, etc? ]( URL_9 ) ^(_36 comments_) 1. [ELI5: What is the difference between Advil, Tylenol, and aspirin? I know they're different drugs, but what is each one doing to my headache/ pain? ]( URL_2 ) ^(_ > 100 comments_) 1. [ELI5: what is the difference between Tylenol, Advil, and Aspirin? ]( URL_8 ) ^(_4 comments_) 1. [ELI5: What's the difference between popular pain medications Tylenol (acetaminophen), Advil (ibuprofen), Aleve (naproxen sodium), and aspirin, and when should each be used? ]( URL_3 ) ^(_3 comments_) 1. [What is the difference between Advil, Tylenol, and ibuprofen and how exactly do they alleviate pain in the body? ]( URL_7 ) ^(_ > 100 comments_) 1. [ELI5: What the difference between Tylenol, Aspirin, non-aspirin, ibuprofen or anything in the headache relief/pain relief department? ]( URL_4 ) ^(_ > 100 comments_) 1. [ELI5: The differences between Tylenol, Advil, and Aleve ]( URL_6 ) ^(_3 comments_) 1. [ELI5:What the difference is between Aspirin, Acetaminophen, and Ibuprofin. What are the pros and cons of each drug and in what circumstances should I use one over the other? ]( URL_5 ) ^(_ > 100 comments_)",
"Ibuprofen and Naproxen are both anti-inflammatory. Ibuprofen doesnt last as long as other non steroid anti-inflammatory like Naproxen. Acetaminophen is to help with minor pains and fevers."
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7mszka | What makes staring into a solar eclipse much more damaging than staring into the good old sun? | Physics | explainlikeimfive | {
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"It's not that it's more damaging, it's that people are more likely to do it. It's painful to look at the sun when it's shining so people don't do it. and they don't have any reason to do it. But with an eclipse, it's like 2 minutes of total solar eclipse (during which time it's safe to look at the sun), and 2 hours of partial solar eclipse that is as dangerous to look at as it is to look at the regular, uneclipsed sun, but that people have motive to look at. So they keep glancing up for a few moments at a time, during which damage is done.",
"Mostly because an eclipse gives people a reason to stare at the sun. It is perfectly safe to look at a total solar eclipse, but people are tempted to look at partial ones as well, and that is where the damage comes in."
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7mt07q | After showers, whenever I rub my skin I get rolls of dirt/dead skin cells. Why is this? | Other | explainlikeimfive | {
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"You need to exfoliate better. Or shower more often. Grab a wash cloth or loofa and wash, don't just use your hands.",
"(disclaimer: I'm no scientist.) Your skin regenerates/replaces itself every 27 days, that means, shedding off old skin cells, and replacing them with new ones. Your entire body does that, just not as fast as your skin does, as its constantly in touch with the outside world. If you dislike your dead skin cells, consider buying something to scrub your body while showering."
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7mt0xl | Why we can't see a full circle rainbow? | Other | explainlikeimfive | {
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"Because of the physical properties of rain droplet, the light entering and leaving forms an angle of about 42^(o). That means a rainbow is going to be a ring \"around\" the sun at 180^o - 42^o = 138^(o), or 42^o from the point exactly opposite the sun. Since that point is below the horizon, the earth itself blocks the lower portion of the rainbow. [But not always]( URL_0 ). If you are at a high enough altitude, the can be enough water droplets between you and the ground for a full 360^o rainbow to appear.",
"You can if you get a garden sprayer and put it in most more and shoot in into the air in a sunny day. The reason you can't see one with rain in the distance us that you are seeing a very large version of the same thing being cut off by the horizon. Every person sees a different rainbow in the sky"
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7mtrki | How exactly does a preservative preserve food and what exactly is a preservative? | Chemistry | explainlikeimfive | {
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"Echoing what the others say, it's all about \"available water\". Salt and sugar does the same thing - draw water away, or make the water too salty/sugary for bacteria to live in it. Things that change the acidity kind of does the same thing - they make the water inhospitable, so the bacteria can't live in it. You can also make a mix of the two, using a bit of vinegar and a bit of sugar. Drying something also takes away the water. * This is what is done with jellies and jam and fruit preserve and a lot of other things - olives too. The only thing that's different from all of these only works on things that are sterile - you can cover the outside in something that's toxic. The toxic thing can be a mold, strangely enough - because the mold makes toxins to protect itself, so other bacteria and molds can't survive. But it means you have to cut the outside away when you want to use it, and then you can't leave it, because you've opened a door for bacteria and different molds to \"enter\". * Camembert is like this - the outer layer is a living mold that kills everything else. The toxic thing can also be residue from smoke because the thin outer layer is toxic, the bacteria can't enter. We can take a big bite of it, though, because the layer is very thin, so there's not enough toxin to affect us. * bacon and fish are often preserved like this",
"All a preservative is, the whole thing, is something that makes stuff not go bad as fast. The two most common preservatives are sugar and salt. They work by soaking up all the water so there is no water left for bacteria, fungi, etc. to use to grow. No water, no growth, means your food lasts longer. I don't know enough about the other types of preservatives, so I'll pass the baton.",
"What I'd like to know is how they preserve lettuce in bags, because they have to do *something*. If I buy a head of romaine and chop it and put it in a bag, it will last a day or two tops before turning brown, limp and useless. If I buy [a bag of chopped romaine]( URL_0 ), that shit stays perfect for up to two weeks. And yet, every single bag says \"Preservative-Free\" on it.",
"Jumping in here, and speaking almost strictly from a microbe standpoint (as opposed to oxidation or chemical degradation) salt and sugar are already mentioned at length and they preserve food by making water unavailable to microbes because the concentration of salt or sugar is too high. Another very common preservative what I don't see mentioned is acid. Low pH also prevents microbes from growing - particularly dangerous ones. This is one reason why you will see anything from baby food to beverages to mayonnaise with acid added especially citric, phosphoric, vinegar, lemon juice, and a favorite ascorbic (aka vitamin C). PH is also a primary reason that beer and wine cannot harbor pathogens although alcohol helps a lot with that too. Speaking of which alcohol is a great preservative and is primarily reason homemade (highly alcoholic) eggnog won't kill you even if it's kept in a bottle for weeks or months. The preservatives you may be asking about are chemicals like potassium sorbate and sodium benzoate which prevent microbes from growing via chemical means.",
"I'm confused about all these comments saying sugar is a preservative I've heard it before and I don't doubt it, but doesn't it feed the bacteria? I swear if I just leave a sugar connection out it will get nasty quick",
"While a lot of these comments do help define the preservative process, there are some major processes that are being excluded from answers here that would be more than helpful at elucidating why spoilage occurs in the first place. When talking about spoilage, it is very important to consider the chemical structure of each chemical species in debate. For instance, the reason why water is evaporated from most foods to help \"preserve\" the food is due to water being a glorified alcohol. In other words, the molecule H₂O contains a -OH group attached to another Hydrogen. In chemistry, -OH groups are highly reactive because of the prevalence of extra electrons on the oxygen atom(In general, any atom with extra electrons is highly reactive). One example the comes to mind is unsaturated fats. Unsaturated fats include double bonds which means these 'double bonds' have 2 extra electrons than a normal single bond. Unsaturated fats or -OH groups will attract electron deficient species to their electron rich sites' and initiate bonding. This is where spoilage occurs. In complex organic molecules, nature prevents against this bonding by adding other chemicals to prevent spoilage. For example, many leaves and plants contain poly(meaning multi)unsaturated fats. Hint: sites where spoilage can occur!! So to protect against this, α- tocopherol (Vitamin E) is added to chemical species at the site of attack and is often referred to as a natural preservative because it prevents the bonding process mentioned earlier which is also known as autoxidation, and therefore food spoilage. Processing of foods can remove the natural vitamin E, so artificial preservatives are added to these foods in order to retard their spoilage. A good preservative usually contains an -OH group surrounded by a bunch of bulking substituent groups with lots of extra electrons. To look more in depth, I would recommend looking up oxidation processes and the chemical structure of 'good' preservatives.",
"Water activity (percentage of water) aside, some microbes do not thrive in super sugary (fruit preserves & jellies), super salty (brined olives) or acidic environments. So yeah, while salt can pull water from foods, it's a touch more complicated than that. Please note that we're talking about food borne microbes, not extremophiles.",
"Why does no-preservative \"organic\" milk last several weeks longer than those normal milks ~~chock full of preservatives~~, in comparison? Ive always been baffled by this discovery. edit- new information learned",
"Direct this question to r/foodscience for better answers. The water activity answers are close, but not comprehensive as there are many classes of preservatives. Some lower water activity, others absorb oxygen, some chelate metals that could act as cofactors in enzymes or act as catalysts in redox reactions, some disrupt cell wall formation of microbial cells... there are many ways to control what grows in our food, and they are often used in conjunction.",
"No one seems to be talking about saltpetre (potassium nitrate), which is also used to make gunpowder. It is surely a toxin, but we use it in the 1/25 ratio to salt range to cure meats such as ham. It can be injected, but if rubbed on in several stages, it leaches far into the flesh on its own. Note: saltpetre can be harvested from guano, or even made from pouring stale urine over mounds of feces mixed with grasses and leaves.",
"So there are a few different types of preservatives, but at least as far as food goes they're generally either anti microbial or anti oxidants. anti microbial preservatives make the food inhospitable to things like bacteria, mold etc. In this case its usually an acid of some sort. Bacteria tend to like very specific PH ranges, so making the food a little bit acidic slows them down. This is no different than pickling or making jams or whatever, we just know what we need to add and how much rather than relying on processes like fermentation. Antioxidants exist to keep fats from going rancid when exposed to oxygen. They can work in a few different ways, but a not uncommon one is reacting with metal ions that can speed up the process of oxidation. Citric acid does both which is why it's pretty commonly used.",
"Preservatives work by making food unsuitable for microbial life like fungus and bacteria, while preserving it's palatability for consumption. For instance if you encased food in crazy glue, it might preserve it, but it would be inedible. So a preservative could be anything that makes it hard for fungi and bacteria to grow, and is added to the food. In other words something you treat the food with, versus the way the food is packaged or stored. Tin cans preserve food, but they are not a \"preservative\" in the same way that salt is. Common preservatives include salts, acidic compounds or base compounds like lye (lutefisk for instance or maraschino cherries) Some foods have natural preservative abilities like juniper berries, certain herbs, etc. The food ingredient list usage of preservative may also include substances which make the food taste better rather than ones that strictly keep the food sterile. These might preserve the texture, color, or flavor. Meats are commonly preserved by drying, salting, and smoking. Fruits and vegetables by pickling and brining. Some foods can be preserved by drying, and treating with sulphur compounds (like dehydrated fruits). Some methods and substances work better for one type of food versus others.",
"Food decays because tons of tiny creatures are eating it and pooping it back out again. A preservative is something you put on or in food that keeps the tiny creatures from eating it and pooping it back out again.",
"I'm hearing a lot of talk of sugar and salt and acid, but I still have more questions: Salt based- why do you need multiple salt based preservatives? I assume sodium nitrate, sodium nitrite and sodium erythorbate have a similar mechanism of action- is it just taste based? What about BHT, BHA and TBHQ, how do these work? How does potassium sorbate work?",
"If you are talking about some of the stuff with very unnatural sounding chemical names...sodium benzoate and sorbic acid are antimicotics and slow microgrowth. TBHQ or BHT are an antioxiant and slow fat containing products from from getting rancid.",
"Hey guys, your local verified Food Scientist here. This will probably get buried but there is so much... wrong here... A preservative on a GENERAL term is anything that prevents food from spoiling. A preservative from the food guidelines has specific rules it must follow. Many things can be used to preserve food. These are broken down into 2 categories: intrinsic (internal) and extrinsic (external). External factors include: packaging, refrigeration, storage conditions etc. Intrinsic factors (what I believe the TRUE question is here) include: pH, salt levels, aW (water activity which everyone keeps talking about) etc. So? FeartheJet; now that I know what a preservative is, can you list a few common ones? Sure, common preservatives are: vinegar, salt, sodium diacetate, acetate, potassium sorbate, benzoates. FeartheJet, why are there so many preservatives? Well, random reddit users, preservatives can protect against different things. Some protect against spoilage organisms (things that don't get you sick but do degrade the quality of the sensory of food). Things like aerobic bacteria and lactic acid bacteria. Aerobic bacteria eat the food you want to eat and \"poop\" leaving behind undesirable flavors. Latic acid bacteria do the same but produce lactic acid and gas (the bloated packages), the lactic acid also causes a drop in pH and makes the food \"sour\". FeartheJet, what other types of preservatives are there? Well, there are things to prevent mold growth, pathogens (bacteria that can make you sick like e. coli, listeria and salmonella). There are also antioxidants which prevent rancidity and oxidations. The real question people are trying to answer is \"why do bacteria grow\" but food isn't only interested in bacteria. Just because there is low water activity (the available water in the product that can be used for growth of microorganisms) doesn't mean things like mold and yeast can't grow; in fact they prefer lower water activity. Low water activity naturally eliminates the ability for high water needing bacteria to grow reducing competition and making it easier for mold to grow. Salts and sugar work by reducing water activity. Other preservatives work by killing the bacteria (kill step) , and other preservatives work by preventing the bacteria from growing (bacterio-static). Hope this helps."
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7mttk6 | Why does your body gasp for air when exposed to sudden contact with freezing water? It seems a bit counterproductive to inhale when wet (e.g falling through a frozen lake) | Biology | explainlikeimfive | {
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"It makes you breathe in quickly because you are potentially about to be entirely submerged in cold water so it makes sense to take as big a breath as you are able. This typically won't occur if your head is the first thing to enter the water.",
"> it doesn't make much sense that your body would make you gasp for breathe when the logical choice would be to not breathe in. Not really addressing what this response is, whether or not it happens to all humans, and what causes it: remember that we humans are just tall, bipedal apes who like all other lifeforms on this planet are products of evolution. And evolution does not reward that which is perfect. That \"makes sense\" or is \"logical\". Only that which is *\"eh, that's good enough\"*. To get enough members of a species to breeding age to pass on their genes, to evade their predators and find sufficient food to pass an environment's selection process. Everything alive today has passed that brutal filter. Everything that didn't is very, VERY dead. So the follow up question would be, *would the urge to inhale on encountering very cold water be a selective pressure that would prevent a large number of organisms from reaching breeding maturity?* And the answer to that question is certainly *no*. Especially considering our species, homo sapiens, originated on the continent of Africa where freezing cold water sources would have been non-existent.",
"The reflex to inhale when exposed to a colder temperature is to stimulate the newborn's first breath after delivery. (I cant find sources though. I think it was two germans who tried to map all reflexes and that was their conclusion.) I dont know if it still holds water. And I fully agree with /u/sovietwomble that this is more beneficial than to not have it. In some cases it might be a disadvantage though. Just that the pros outweighs the cons."
],
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8,
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7mu4pl | would sodium chloride gas conduct electricity? | Chemistry | explainlikeimfive | {
"a_id": [
"drwn2z2",
"drwnlxg"
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"text": [
"As far as I remember, sodium chloride gas does not exist as Na^+ and Cl^- ions, but rather a mix of a monomer (NaCl) and a dimer (Na*_2_*Cl*_2_*), and therefor the elctrons aren't free to move like they are in a Na^+ Cl^- solution",
"Compounds only ionize when they're forced to. Compare waters polar properties when it interacts with NaCl with NaCl in a vacuum. The NaCl in a vacuum will stay together as a compound and the NaCl in water will have solvation effects (it will be surrounded and ionized). Inside ambient air, its the middle ground, with it only ionizing on the very rare collision with multiple molecules of water. Chlorine gas (Cl_2) has a mediocre ability to conduct electricity. One chlorine is contently bonded to another chlorine, allowing for electron movement through an electrical emission. Chlorine gas also sees its molecules being very far apart from each other, so its ability to conduct electricity depends on a bit of physics (luck) and a bit of estimation due to the ideal gas equation. It does not have the capacity of freely moving electrons like metals do, and so it would not be too good at conduction."
],
"score": [
4,
3
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7mukga | what exactly is phlegm and why does it change colour based on our health? | Biology | explainlikeimfive | {
"a_id": [
"drx12fp",
"drx1uuz"
],
"text": [
"It's mucus. Snot, just like the stuff found in your nose. People think of mucus as being found only in the nose, but there's a layer of it that coats your entire respiratory tract, from your nostrils all the way down into your lungs. It cleans the air you breathe by acting like flypaper: dust, smoke, germs, etc. get stuck in the mucus before they reach the lungs. Wavy hairlike structures called cilia push it into your throat, where it drops down to your stomach to be destroyed. You only really notice phlegm when you're sick, because the flypaper starts getting saturated with germs and with dead immune cells. This changes both the color and the consistency of the phlegm. Also, your body starts secreting a whole lot more of it to help fight off the infection.",
"\"Phlegm\" is the term we used to describe mucus that happens to be produced by your throat and lungs when you're sick. It's the same basic stuff as the mucus produced by the lining of your nose, sinuses, throat, and gut, but we only call it \"phlegm\" when it comes from the lining of your respiratory system (i.e., throat and lungs), and when it's produced in excessive quantities as part of some disease process. I say \"disease process,\" but that doesn't have to mean *infectious* disease. There are a variety of ways of abusing your airways that can lead to excessive mucous production, i.e., phlegm. Smoking. Air pollution. Allergies. Shouting or even talking too much/loudly. Pretty much anything that's going to cause inflammation in your throat or lungs, basically. That's just how your throat and lungs respond to inflammation. But what *is* the stuff? Protein, mostly. A water-based solution of proteins, to be slightly more descriptive. What *kind* of proteins? I think the chemical distinctions between different types of proteins are beyond the scope of ELI5, so let's just say \"protein\" and leave it at that. Now, why does the stuff change color? A lot of reasons. [Here's a great article on the subject.]( URL_0 )"
],
"score": [
17,
7
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[],
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"https://www.healthline.com/health/green-phlegm"
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|
7mus96 | Why is it so hard to rip open a package with wet hands (even if it has a notch for ripping)? | It seems like I can get a proper grip but it just doesn't go. | Physics | explainlikeimfive | {
"a_id": [
"drwrzcu"
],
"text": [
"When your hands are wet they are lubricated by the wetness. This reduces friction, which reduces your ability to grab and rip a package open."
],
"score": [
3
],
"text_urls": [
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} | [
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7muwuz | Why do so many injuries/illnesses improve so dramatically after a NIGHT of sleep as compared to an entire DAY of similar bedrest. | I've had numerous sprains, bruises, colds, fevers, etc. where I lay in bed all day long and show some improvement, but a night of sleeping where I do virtually the same thing (lie in bed) often shows exponentially more improvement. | Biology | explainlikeimfive | {
"a_id": [
"drwtbhh",
"drwtjga"
],
"text": [
"Sleep cycles are when your body releases growth hormone. So that's the time when tissue that has been damaged by the injury/illness gets repaired. Essentially, you wake up stronger than you were when you went to sleep. This doesn't happen during periods of consciousness, only when you reach REM sleep. So \"resting\" without sleeping won't have the same effect.",
"When you're sleeping your energy expenditure is reduced nearly half. Think of it as a running car, when you're laying there you're still awake in idle, but when you're sleeping you're \"off\". It's important because that energy can be utilized for the healing process. Also when you're away a large part of your blood flow is to your gut and muscles which also reduces when you sleep, which allows for blood to go to the areas that need healed. As for a sickness, when you sleep you make more white blood cells that can attack viruses and bacteria."
],
"score": [
12,
6
],
"text_urls": [
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} | [
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7mv2pb | Why does hearing a song lots make us dislike it? | Other | explainlikeimfive | {
"a_id": [
"drx1fp8"
],
"text": [
"I think you can relate this in a similar way to drugs. When you take a dose of drugs or listen to pleasant music, your brain is simulated and releases signals that it is happy with whatever you consumed. However, over time the same stimulus will result in lower and lower stimulation in the brain, as it becomes used to that stimulus. This is why many drug users have to take increasingly high amounts of drugs to attain the same high. The more you listen to the same song, the less pleasure you will get from it. But unlike drugs, you can’t increase your “dosage” of music. You can’t listen to a song twice at the same time. So, over many listens, you eventually lose all pleasure you gain from listening to that song, and it becomes boring."
],
"score": [
3
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"text_urls": [
[]
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"url"
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|
7mve2z | How and why do spider webs become cobwebs? | What processes go into webs becoming cobwebs? How do the webs lose their "stickiness"? | Biology | explainlikeimfive | {
"a_id": [
"drwx4x2",
"drwx7oj"
],
"text": [
"> How do the webs lose their \"stickiness\"? They get covered in dust. Spiders frequently rebuild their webs in new locations. The old, abandoned web ends up collecting dust, which makes it less sticky, just like covering a piece of tape with dirt and debris makes it less sticky.",
"i believe its an accumulation of dust and detritus on the web. imagine a sticky piece of scotch tape, laid face up, and you blow a weeks worth of accumulated house dust onto it. all the dust will stick to the sticky part of the tape, making it not sticky any longer. same concept, i think."
],
"score": [
21,
3
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"text_urls": [
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} | [
"url"
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"url"
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7mveyk | If I have a 1/50 chance of winning and I try 50 times, why is a win not guaranteed? What would the actual odds be? | Mathematics | explainlikeimfive | {
"a_id": [
"drwxnrq",
"drwxd51",
"drwxeiy"
],
"text": [
"> If I have a 1/50 chance of winning and I try 50 times, why is a win not guaranteed? For the same reason that if you flip a coin and it lands on heads, it's not guaranteed to land on tails the next time. Each event is what's termed an \"independent event\". The coin (or whatever device/situation you're dealing with) has no memory. It doesn't know what happened last time. Your 50th attempt to win something is identical to someone else's 1st attempt. > What would the actual odds be? The way to calculate the odds of winning at least once after 50 attempts is by calculated the odds of *never* winning after 50 attempts, and subtracting it from 100%. So the odds of not winning on the first attempt is 49/50. The odds of not winning on the second attempt is likewise 49/50. So the odds of not winning 50 times in a row is 49/50 times itself 50 times, or (49/50)^(50), which comes out to be approximately 0.364, or 36.4%. So the odds of winning at least once after 50 attempts is 100% - 36.4% = 63.6%",
"Each attempt has a 1/50 chance, each previous attempt’s success or failure to win has no bearing in your chances on subsequent attempts.",
"Each attempt has a 1 in 50 chance of winning, but they're all independent attempts. We can reframe your question another way. If you have a 49 in 50 chance of losing, what are the chances you lose 50 times? We take (49/50) and multiply it by itself for the number of attempts and see that you have a 36% chance of losing every single time, which means your odds of winning at least once are 64% Now, if you have a 1 in 50 chance of pulling a yellow marble from a bag of 50 marbles and don't put the marbles back in after each draw, then you no longer have independent events and after 50 draws you'll have pulled all the marbles and must win. If you put the marbles back in the bag then you're back to independent events and may never win."
],
"score": [
28,
18,
5
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|
7mvp76 | Why is it that nebulas or certain parts of galaxies are pink, blue, green, etc... | Also, if you were inside one would the "sky" be pink (or whatever color it is) if you looked up? | Other | explainlikeimfive | {
"a_id": [
"drwzner",
"drx0fqe"
],
"text": [
"They aren’t, in reality you can’t see nebulae with the naked eye, most photos you see from Hubble are in various infrared and different scan types Edit: spelling",
"They're digitally colored. they don't really look like that"
],
"score": [
7,
3
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7mw981 | why we sell gas by the volume but not mass, unlike in avionics and auto racing? | Other | explainlikeimfive | {
"a_id": [
"drx55da"
],
"text": [
"Planes and race cars care about how much weight they're moving around as it has a significant impact on performance. A plane needs more power to get more weight off the ground so extra mass is a problem for it if you happen to fuel it on a cold day Passenger cars don't care as much about added mass, and people know they have a 10 or 12 or 15 gallon fuel tank, not a 64, 96, or 128 pound fuel tank. We generally measure liquids by volume not mass, you can see this with baking instructions too We also don't meticulously temperature control gasoline. Put it in a big underground tank and it'll stay around the same temperature all year long. Even if it does go through temperature swings, it doesn't change in density that much. At 0C gasoline is 1.8% denser than at 15C, and at 30C it is 2% less dense than at 15C, that's not a huge swing"
],
"score": [
6
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