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bv9f4x
|
Wrinkle resistant/non-iron clothing
|
It depends on the material. Natural fibers like cotton and linen wrinkle easily, though wool does not. Basically, cotton fibers (for example) have little elasticity - check a shirt or jeans, if you can find some with 100% cotton and see how well they stretch compared to other fabrics. They do have a little, but not much. Cotton more than linen, for example. That is why they don't bounce back as easily to their original shape - winkle free.
Most microfibers (like polyester) are the opposite - like sports clothing. It doesn't wrinkle, and has a "memory" of it's original shape; as it's really stretchy, it can bounce back to the memory position of the fibers - unwrinkled.
That's why it seems "modern" - we haven't been able to produce microfibers for all that long.
Edit: Not all cloths are made that way because natural fibers have other benefits (e.g lack of smell development for cotton, lightness of the fabric for hot climates for linen) and many people feel more comfortable with them than with synthetic fibers.
|
72a18be6-cc88-4b33-89cd-2cbe5505a430
|
bv9o4o
|
Why does FedEx always have to shoot your package to the other side of the country before delivering it when it's two states away or less?
|
It’s like carpooling. Even though you might find it faster to drive just you in a straight line to work for 15 minutes, it’s more efficient to go a bit out of the way to pick up extra people. One car driving 30-45 minutes is better than 5 cars driving for 15 minutes each.
In the same way, packages are all sent to distribution centers. Various areas have their own centers, and different centers handle different transport types and such.
So even though it would be faster for *your* package to hit a truck and go straight to you, there might not be enough packages from that one center to your area.
The number of packages coming from “Littletown, Virginia” going to “Anywhere, Dakota” aren’t numerous enough to send directly one at a time. To save costs, they ship all packages going to “Anywhere, Dakota” to a central facility, where they’re all shipped out in a massive delivery. This means it might take a little longer for some individual packages, but the overall process is much more efficient.
|
adf269b8-a675-4fdb-a01d-9ab2c88a11aa
|
bv9q5j
|
When products like Crystal Pepsi are re-released, why is the recipe and packaging different?
|
Because if it wasn't working before you don't do the same thing again, change it up and hope it works
|
c3c015a4-332c-44d2-8c62-a0b16e70c290
|
bv9wz2
|
What's the cause of the "Elmer Fudd" speech impediment where r's and l's come out as w's?
|
When you're speaking, you're not just using your vocal cords. You also use your lips, your teeth, and your tongue to pronounce words. When one of these doesn't work properly, you can't properly pronounce sounds that rely on that part of your body.
The reason L and R are often mispronounced is because they need you to precisely control your tongue. If you can't do that, maybe because of a disease or maybe because you just didn't practice enough, your tongue will be in the wrong position and you'll say something similar to a W instead.
Imagine you're saying the word 'peel'. The P is pretty easy to pronounce - you close your lips for a split second, build up a little air in your mouth, and let it explode out all at once. The 'ee' is also easy - you close your mouth halfway and just let the sound come out.
The L is harder, though. You need to gently press your tongue against your teeth so it almost, but not totally, covers them. This is a lot harder than popping a P or squeezing out the 'ee'. Try pronouncing 'peels', but keep your tongue perfectly still. It sounds a lot like a certain Nimrod!
The American R is even harder. Not only do you need to bunch the back of your tongue up, but you also need to clench your teeth and let a tiny bit of air out of your throat. If you don't clench your jaw, your R sounds like a British R, more like an "ahh" than an "arr". If your tongue isn't bunched up enough or your throat is too open, you make a W sound instead of an R.
The S sound is also hard for the same reason. Your tongue needs to be positioned just right to let out a little hiss of air. If it's even a little bit out of position, you'll say 'peelth' or 'peelf' instead of 'peels'.
Because of how difficult these sounds are to make, they're really common speech disorders.
|
8b9bc28c-e072-4cea-887e-a10f961df875
|
bva9ce
|
The physic of the shadows on this image
|
It isn't an effect of the light source's location (it is the sun) but rather due to the lens in the camera being used. The field of view of the lens is such that lines aren't always parallel across the scene; we aren't Picasso here.
|
e7dc3631-799b-4703-a276-738e65bec544
|
bvaczk
|
When you delete stuff from your phone (pictures, videos etc.) where does all that data go?
|
Actually nowhere. Imagine storage as a bunch of words in a notebook. When you "delete" something you actually are just telling your computer (phone) that you don't care about the contents of the notebook anymore. You throw that notebook in a pile that you designate as "good to write in". The notebook isn't actually cleared, you just no longer care that it has anything written in it.
Now when you have something else to write, you take out that notebook and simply write directly over the last thing that was there. The last thing isn't "deleted" per se but is overwritten.
Actually with many programs you can look at your own storage and see if there is enough of your previous files to restore them from storage. If you never want this to happen (or you're doing some shady stuff) there are programs that essentially are data "shredders". They continuously overwrite a certain memory location until the data is completely unrestorable. From the analogy earlier it's like if you took a permanent marker and just kept drawing over all the pages until you couldn't make out what was underneath anymore.
|
7f8893fe-605d-4e2a-b934-b32c71b58d15
|
bvaedo
|
What happens to astronauts tears when they are in space?
|
They tend to pool up and cloud their eyes due to surface tension. [Inside the confines of a space suit this can actually be quite dangerous, several spacewalks have been cancelled or cut short because of fluid in a space suit.](_URL_0_) Chris Hadfield also talks about one time he sneezed or something in his helmet and it was super bad, I'll try to find it.
|
6efa8d20-3dce-4874-8938-4a4b4b1926e6
|
bvaizk
|
Why shouldn’t you cross your legs when checking your blood pressure?
|
Anything that impedes blood flow will change blood pressure - think like kinking a hose. Even a tiny bit will cause greater pressure behind the kink and reduced flow after. So it’ll give an inaccurate reading. You want to be as open and relaxed as possibly to get the most accurate reading.
|
67688eb5-3143-42b7-b0bc-d16a149edbcd
|
bvans3
|
Why do people always say "false rape accusations are extremely rare" when a false rape accusation happens?
|
Because if we get into a mindset that rape victims are liars, then rape victims will be less likely to report when they are attacked.
Among rape victims, many are unable to directly accuse an individual because they cover their identity. Of those that accuse their rapist, most of them are telling the truth. They at least believe that the accused raped them.
The type of person who maliciously accuses an old boyfriend of raping them, just to get them in trouble is exceedingly rare. More common, but still rare, is the type who accuses someone else because they fear reprisal from the rapist.
But those kinds of lies or half-truths can damage the reputation of rape victims in general, so it is important to remind people that false rape allegations are not common in the slightest.
|
d17ca50d-1510-4245-b723-a6c01c1c03b0
|
bvaq6d
|
How do players playing high intensity sport don't have the urge to go to the toilet in the middle of the game?
|
When you exercise, your body releases adrenaline into the blood. This is responsible for activating the "fight or flight" mechanism. When this happens, your body prioritizes what areas of your body need blood and oxygen more. Your body isn't very good at determining if you're playing sports or running from a bear, so it will respond in essentially the same way. Your body doesn't need to digest food or make urine when you're running from a bear, your muscles need that oxygen to run away! So it reduces the blood flow to your intestines and kidneys and shuttles it off to the organs that need it more. For this reason, your body doesn't produce nearly as much urine or feces during periods of high intensity exercise as it normally would.
|
ba1615d4-0d7c-4724-abc3-d6357bb562e0
|
bvay7a
|
why is Australian internet so bad compared to the rest of the 1st world?
|
Is it? It's a bit higher than the world average, and not so low as to really notice on the overall rankings. Of course it underperforms compared to the top 10.
& #x200B;
Ultimately the poor performance of Australian internet is down to two things; your politicians don't want to fund it (an attempt was made, but was later repealed), and the vast empty space between the major city centers means building and maintaining infrastructure is less cost-effective and reliable compared to satellite.
|
636d7d36-a804-4742-a0fa-0e865981c2b9
|
bvb3jp
|
Why are vets able to be so much more precise about price than human doctors?
|
Because people doctors have to deal with insurance companies and never know how things are going to be priced. In other words, MDs have little to do with billing.
|
4d8e87e7-9ff2-407d-9857-a16e3d3c920c
|
bvbu18
|
So with all the recent space developments, how come it is taking so long to send man to the moon again if this has already been successfully done and all the necessary technology exists?
|
Two reasons, really: money and safety. When we were in a race with the Soviets, this country was willing to spend a lot more money to make it happen. That meant more engineers working on the problem, faster testing timetables, and less of a concern for the price of each component. The other factor is safety. We were willing to take more risks then, which meant less testing and a higher probability of failure. It didn't guarantee failure, which is why it worked out in the end. Today we require more proof that a system is safe, especially when it involves human lives. Since there is less money and more testing is required, we want more cost effective rockets and lunar landers, which takes more engineering to create.
|
105aedb2-ac9c-4f9d-b9b7-e545f42461b7
|
bvccyu
|
- Energy Transport Systems
|
Glycolysis is the first step in all respiration, whether aerobic or anaerobic. You're constantly doing it as necessary to maintain enough ATP and ADP to run your cells.
When you're idle or lightly exerting yourself, it's all aerobic respiration. It's efficient, which is a key part of powering our huge brain and huge legs.
The problem is that it's slow. You need to inhale a bunch of oxygen, transport it into the middle of your cells, do a bunch of crazy chemical reactions, get the byproducts out of your cells, and transport the carbon dioxide to your lungs. Most of the time, this comfortably powers your body and provides a nice reserve of energy-storing ATP in your bloodstream.
When you exercise, you quickly consume all that ATP in your blood. Eventually, you overload your aerobic respiration - you literally can't breathe fast enough to get enough oxygen in and enough carbon dioxide out.
That's when your anaerobic respiration kicks in. This process is faster and doesn't require oxygen or produce CO2. The downsides are that it's not very efficient, and it converts an important chemical for aerobic respiration into useless lactic acid, which later needs to be converted into CO2.
Metabolism deals with getting that glucose into your bloodstream from food. During digestion, your body will salvage many chemicals from food you eat, but others will be metabolized into glucose or stored as fat in lipid cells.
If you don't eat enough food to replenish your blood glucose, well, you'll get hungry. Your body is OK with maintaining a low level of energy stores - after all, our caveman ancestors couldn't hunt three meals a day. The human body disregards a brief diet.
Eventually, if you're chronically malnourished, your body realizes that food isn't coming, and it needs to hit the reserves. You literally begin eating yourself, a process called catabolism. You start with reserves of glycogen in your liver, then in your muscles. If you're still not getting enough calories, your body starts eating the lipids in your fat cells, and you lose weight! Yay!
This is why it's important to diet and exercise together - your fat cells are reserved for desperate circumstances - that is, weeks of undernourishment. You need to trigger this process by spending way more energy than you ingest, long enough that your body thinks you're in a famine.
If you keep dieting or overexerting yourself after the point where your body fat is depleted, your body's only option is to catabolize your muscles, and you start to wither. Don't do this - not only is this dangerous, but the byproducts are toxic.
By the way, catabolic processes aren't fast enough to keep up with respiration. Once your blood glucose and glycogen reserves are totally depleted, and there's nothing in your blood that can be easily converted to glucose, you collapse of exhaustion.
|
1843f94d-42e7-48b6-aa10-2f68859a10aa
|
bvcjig
|
Why it is effective to drink hot tea on a warm day to cool down.
|
_URL_0_
It triggers your body to start sweating a lot, so if the humidity is sufficiently low, that sweat evaporates, taking body-heat with it, resulting in a net cooling effect.
Note that this would not work in high-humidity areas, and it's a bad idea if the individual is already suffering from dehydration or heat shock/stroke.
|
df97f243-f988-4d9d-8300-afd69470717c
|
bvckqn
|
in circuits analysis, there is 3 domains, time , frequency and complex frequency, what is the complex frequency?(S domain)?
|
The extra information is the phase of the signal.
A example would be if you take a simple sine wave and split it and let it trough a inverter that would be the same as a phase shift of 180 degrees. If you then add the signals together the result would be 0.
But just looking ant the signal in frequency domain before and after the inverted they would look identical and you could not determine what happen if you add them together or assume by misstak that you hade a sine with twice the amplitude.
& #x200B;
If you have complex frequency the magnitude of it would be identical the angle between the two would be 180 degrees and the sum of them would be 0.
|
13c27541-d98d-4d62-9c00-9c6c2ff45474
|
bvcw18
|
Why do different elements burn different colours in flame tests?
|
It’s to do with the number of electrons in the outer shell of the atoms, how much energy they absorb and give back when they burn, and the wavelength and frequency of the energy emitted in doing so.
|
4719ade4-f1d3-4967-af45-8f82a9cb8c71
|
bvcyym
|
Why aren't Great Danes and Chihuahuas considered separate species? When does speciation occur?
|
If it fucks, makes a baby, and that baby can fuck and make a baby? Same species.
Fuck, make a baby, but that baby cab only fuck and not make more babies? Related genus but not the same.
Can fuck bug not make babies? Completely different species.
Can't even fuck one another? Not trying hard enough.
Can't fuck but can impregnate you? Xenomorph. Or even worse, a wasp species.
|
2da12f6d-658e-431a-b29a-9676484ba846
|
bvd844
|
How does cloud computing work?
|
"There is no such thing as the Cloud, it's just someone elses server."
Basically instead of having servers and equipment onsite for your business you can rent servers from a 3rd party.
The term cloud refers to a concept in networking akin to 'black box', in that you know it works but you have no idea what's going go inside.
The big upside to Cloud computing is that someone else takes care of the hardware and infrastructure for you (power, cooling, etc) so you don't need onsite facilities and staff to maintain it.
The downside is you often have very little control of the hardware, what's used, who you share it with, where it's located, and how often it's maintained.
Many businesses that operate on the Cloud model operate with an 'out of site, out of mind' mentality and assume it's the cheaper route, which is not necessarily the case.
|
ee2040ff-b492-4939-9ab2-467475f0d1b2
|
bvdhbq
|
How do automatic blood pressure cuffs/machines know when to stop inflating the cuff for each individual person?
|
Basically, vibrations from blood pumping through the arteries are detected by the device, which let it know how far to inflate and when to deflate.
"The new models use “fuzzy logic” to decide how much the cuff should be inflated to reach a pressure about 20 mm Hg above systolic pressure for any individual. When the cuff is fully inflated to this pressure, no blood flow occurs through the artery. As the cuff is deflated below the systolic pressure, the reducing pressure exerted on the artery allows blood to flow through it and sets up a detectable vibration in the arterial wall. When the cuff pressure falls below the patient's diastolic pressure, blood flows smoothly through the artery in the usual pulses, without any vibration being set up in the wall. Vibrations occur at any point where the cuff pressure is sufficiently high that the blood has to push the arterial wall open in order to flow through the artery.
The vibrations are transferred from the arterial wall, through the air inside the cuff, into a transducer in the monitor that converts the measurements into electrical signals."
Source: _URL_0_
|
d27840db-9630-49ce-9d5b-93d1070a4217
|
bvdhf1
|
Why does boiling foods like soup make them last longer?
|
You mean, like in the fridge or as leftovers?
Boiling kills bacteria. Therefore, when you boil food together into a soup, you've killed the bacteria that could cause the food to go bad. If your workstation is clean and completely uncontaminated, then it is very unlikely that new bacteria/contaminates will be reintroduced.
|
dfd2d52a-7d9d-446c-ab30-e242b586a9a8
|
bvdhxx
|
what's that line on a Woman's belly coming up to her bellybutton and why do sometimes women that never been pregnant gets it?
|
The line is called “linea nigra” (Latin: “black line”). _URL_0_
It is caused by hormones during pregnancies and can happen rarely outside of pregnancy, e.g. during puberty, probably also due to hormonal stimulation of the cells in the skin that make it darker in this small region.
|
6ca7a04d-e645-4f88-bbd3-4323667b485d
|
bvdj1h
|
I took the bus for three hours total today. The way home felt way shorter than the way there. Why is that?
|
Your perception of time is based on how many memories you made during those times. Your emotions can also affect how these memories stick.
Taking the bus to there for the first time generates more memories than taking the same route back. Maybe you were anxious to get to your destination or excited about what you wanted to do. On the way back, you'll be more tired and feel like you just want to go back.
The same thing happens when we watch shows for the first time. The first time we see the intro sequence for a show, it seems quite long because they are fresh memories. After going through multiple episodes, the repeated intro seems to go by quickly.
Be careful that your days don't become too routine or else time will slip past you!
|
0dcf99c3-9db7-421d-b995-dbba90081698
|
bvdlwf
|
Why is the land west of the Nile greener than the east?
|
Its probably downhill.
Does your map show relief? You should be able to see contour lines indicating uphill or downhill
|
617be22e-804d-4d76-8bfa-8161fee5530e
|
bvdxoa
|
how are toothpaste company’s able to measure shades of whiteness on your teeth? Like in ads when they claim to “whiten teeth by 4 shades”. How do they do this?
|
A shade is taken to be the smallest change that is visible. That is, if it whitened your teeth by four shades, then you could put three intermediate photos between the "before" and "after" pictures, and be able to see a visible difference between each of them.
Whether the toothpaste can do that is a separate question...
|
bdb6cbbe-55be-45ea-9921-a80b087cd442
|
bvdzoi
|
How do index funds follow their indices?
|
There are two types of index funds--mutual funds and ETFs.
Mutual funds are not "a separate stock". They don't trade throughout the day. They only trade once a day while the markets are closed, and trade at the NAV (net asset value) computed based on the closing prices of all the stocks it contains. So it can't have a trend of its own.
ETFs do trade like stocks. They can develop a trend of their own, but there are "authorized participants" who can break a large block of ETF shares into the proper number of shares of all the underlying stocks, or the other way around. If the ETF trended too far away from the aggregate of the shares it holds, then the authorized participants can make money by doing this trade in whichever direction makes sense, and by doing so they will correct the trend.
|
05804712-0736-464e-b8f3-c4c49a61add1
|
bve688
|
Why does water take time to boil on the stove, but immediately stop once taken off the stove?
|
There are two parts to boiling.
Raising the temperature to boiling point, and actually converting the water from liquid to gas once it’s at that temperature. Both parts require energy (from heat)
When you heat water up to that boiling point, it hasn’t actually boiled yet. You need to keep heating it, adding energy, in order to convert water to steam.
As soon as you take the water off the stove, that process of water turning into steam stops because energy is no longer being added.
|
00a15ccd-ad4d-47c0-92c9-8348b7ee8c1b
|
bve93g
|
radiation, why is it so bad for humans?
|
Radiation can cause a random mutation in a cell that in turn could cause a cancer to develop, increase the amount of radiation and you increase the chances of this happening and becoming lethal.
|
2e84fc52-020b-4587-8bba-bbd4ad87846d
|
bveaaj
|
When media outlets say x amount of people watched a certain game, how do they calculate that number?
|
They don't calculate it. Generally these estimates are from Nielsen, a company that specializes, among other things, in gathering TV viewership data.
Nielsen has select households, called "Nielsen Households" which they gather viewership data from (and they get data in lots of other methods), from this small sample of people, they extrapolate to get an estimate of the total amount of people that watched.
|
cd06f446-5ea7-4ea4-b97c-98e6b95b4d5a
|
bvegn3
|
How does the moon control the tides with gravity?
|
The moon's gravity squeezes the oceans causing it to bulge in the side facing the moon and the opposite side. The earth spins through the tides even though it looks like the tides are moving in or out themselves.
|
648c189e-e401-4a22-ac58-4678a842c316
|
bvemi6
|
Why do humans fidget so much?
|
Moving around on your chair in certain ways changes weight distribution on your ass and makes it more comfortable. Over time we naturally slouch and sink so the weight distribution changes up again putting more stress on your butt and legs. That's why people who are more cognizant of their posture tend to move around and fidget less.
|
3b45e889-6344-4e94-9e3a-d0b00bcc6aa4
|
bveqj5
|
The difference between the Conservative and Labour parties. (for people well versed in UK politics)
|
More or less the same as any centre left and centre right party in mainstream politics around the developed world.
& #x200B;
The Conservatives are relatively more pro big business, lower tax rates and corporation taxes, less regulations on the economy, resist expansion of the welfare state and social provisions + pro austerity measures, want less nationalisation of the economy (eg. oppose nationalising the railways, have privatised certain components of the NHS), etc. Socially they are slightly more traditional ie. take harder stances on things like drug laws and opposed gay marriage moreso than Labour.
& #x200B;
Labour are essentially the reverse of everything mentioned.
|
4cf1cf59-8521-4a69-bb59-0fd87bfa55ea
|
bves04
|
How does the cold virus - as opposed to the immune response - actually operate?
|
A virus reproduces by injecting itself into a cell, forcing that cell to make a shitton of copies of the virus, and then bursting the cell to release the copies. You wouldn't last long at all without an immune system. My gut reaction is that *any* virus would be fatal in that case.
There are still people who have poorly functioning immune systems. We call them "immunocompromised" and it's very dangerous if they get sick.
|
7e0add29-3730-4d07-8a77-0179dd8e0e89
|
bvet5l
|
How/why do speech impediments happen?
|
Not all speech impediments can be traced to the same cause. Some may be the result of under-developed musculature in the face and tongue, in which case speech therapy will likely be particularly effective. Some may be the result of neurological damage in speech or language regions of the brain. Some may be psychosomatic, due to traumatic experiences or mental illnesses.
|
b0901c08-90ee-44c5-930a-c6cda40ff9c0
|
bvf2nx
|
Why hasn't Tesla's wireless transmission of electricity been implemented in modern technology?
|
It's not very efficient. It's possible to transmit power wirelessly, but wires are cheaper and more efficient.
|
ef230d0c-4303-4266-806f-7a559f28d341
|
bvf9dq
|
Why, or how does being poor or having bad credit cause insurance companies to charge more for insurance?
|
They run a risk analysis on how likely you are to cost the company money.
Overtime there have been connections between poor/bad credit and increased payouts, so they charge people higher rates based on that
|
cb74369c-97ea-4076-a9ba-4472c9558eea
|
bvfhwj
|
Why does it take longer for wounds to heal in Winter?
|
Colder temperatures can slow blood flow. Your blood contains a chemical named: fibrinogen. When you have a wound, this chemical will be converted into another chemical named fibrin by a special enzyme called thrombin. The fibrin will form little wires on the wound (you can't see those, they're too small). Your blood also contains little platelets which will get 'stuck' into these wires. This network will harden up and you'll have that crust on your wound.
& #x200B;
So basically: if your blood flow is slower, less blood will be transported in a period of time. This means the transportation of fibrine and platelets from point A to B is slower and thus takes it longer for enough fibrine and platelets to reach the wound.
|
e1265325-6c62-463c-84fa-e880641bc637
|
bvfiio
|
- Why so bubbles form inside a glass of water at room temp if you let it sit long enough?
|
There are two important parts to your question. First, water that you drink from a tap isn't entirely "water" - it has bits of other things like salts dissolved in it, and that includes air and other gases. Normally, these gases are quite happy to stay stuck inside the water, and very rarely run into each other. This is where the second part comes in.
The inside of a glass isn't totally smooth - there's roughness and texture that you can't see, whether the glass is made of actual glass, plastic, or anything else. The rough parts of the glass make a perfect spot for the gases in the water to attach to. Once a tiny bit of gas is stuck to the wall, it allows other bits of gas to attach to it. After enough time and enough accumulation, this gas becomes a proper bubble.
So your theory is partially right - there are microscopic bubbles forming inside of the glass, they're just dissolved gas coming out of the water rather than water turning into vapor.
|
05213871-4eb5-41a6-ad09-da669f58708f
|
bvfsaf
|
How are we able to sleep much longer when we are sick compared to when we are healthier?
|
Your body is made of little animals. Those animals need food and water and rest. Those animals each do a job and can switch around and go where they are needed. Sicknesses and viruses are other animals our bodies don’t like. Some of our little body animals are used to go and kill the virus animals. When we sleep our animals can stop doing their jobs and take care of the virus animals so they stop hurting us. We sleep longer so that our animals called cells can kill the viruses
|
59a685ed-3a8e-4bb8-99ed-7ac9c6bddef7
|
bvfux3
|
How does a capacitor work?
|
A capacitor is two conductors seperated by a thin insulator. The conductors are close enough to interact but not enough to transfer electricity. This allows charge to build up on one of the conductors. The charge can then be dissipated all at once by completing the circuit. The capacity depends on the size/ammount of electrolyte used as an insulator and the size of the conductors.
|
fbd262f2-e5e5-4dfa-9685-dcffacb54f72
|
bvfz02
|
Why are some state lines smooth, while others are jagged?
|
Most of the wiggly ones are set to follow rivers, or in some cases to follow where the rivers used to be back when the lines were drawn. Back in the 1800s, it was a lot easier to say "Kentucky is this side of the river, and Missouri is the other" rather than try to pin down latitudes and longitudes.
In places like the midwest, with fewer natural boundaries, lines would just be drawn on a map and measured by surveyors. In a lot of cases, these lines were drawn before the territories were even settled by the US gov, so nobody was even really out there to say what good natural boundaries would be.
Edit: So, for example, the wiggly part of Texas follows the Red River, but the Red River keeps going East/West and somebody decided they wanted Texas to go north, so they lose the nice natural boundary and switch to "drawing lines on a map" mode.
|
3ab88f15-475e-4983-b47c-277095ba9fd6
|
bvggba
|
Why do City lights flicker when seen from a distance?
|
Two reasons that I can think of. One is particulates in the air, like dust, that changes how much light gets through. As dust moves around, it blocks some light, which you'll see as flickering. The other reason is light refraction due to humidity and temperature variations.
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8ef75bec-7f3a-430b-ab3e-abe1dc1ccfe6
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bvgggo
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Does increased load on a generator require more mechanical work.
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Current flowing through the coils of a generator makes an magnetic field. The more current, the stronger the magnetic field. The higher the load, the more current. This magnetic field is opposite to the one generated by the magnets of the generator.
The gasoline motor is trying to move the magnets past the magnetic field generated the the coil. The stronger this field is, the more work the gasoline motor needs to do.
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363177b3-4c53-4e71-a0ea-3777474032f4
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bvgj6b
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why does the power go out in rural areas more than in the city?
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Redundancy. Think of the power grid as roads. In a big city there are 10 different routes you can take to get to any destination. Out in the county, you've got maybe 1-2 options to get to most destinations. So take out 1st Avenue in town, and the power has 12 other ways to get to you. Take out County Road 82, and everyone who lives on it is in a blackout.
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16ad7218-04c4-4962-90a6-839243976c59
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bvgru5
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How poor, homeless people survive, especially in 3rd World Countries
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I live in South Africa, and we have landfill pickers too.
Simply put, they live a life of true poverty. Their houses are crude A-frames constructed from materials they find on the landfill or in the trash - sheets of plastic over sticks lashed together just well enough to keep the weather out. They live at the landfill/sorting ground on vacant land.
Their clothes have holes in them, are caked in dirt and smell of wood smoke, likely picked from the very landfill they live on. They have no healthcare, or access to social grants. Many of them aren’t even citizens and so couldn’t receive much even if they were able to make the journey to apply for such things. They look aged beyond their years.
Staple food is cheap. A kilogram of maize meal here is R10, that’s less than a dollar to feed yourself for at least two days. They can’t afford much more than this. Some canned tomato and onion might be a treat if they have a good day. Many are slowly starving and in no way receive adequate nutrition.
So the take away? Food is cheap, and you can survive without everything else if you absolutely have to.
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36c16bdb-44d6-413b-8465-2b023bfc4ec9
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bvh5al
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What process, chemically speaking, makes you feel hungry and your stomach rumble?
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What makes you feel hungry:
& #x200B;
When your stomach is empty, your stomach starts producing a hormone called Ghreline. For the biggest part this hormone is produced in the stomach. In your stomach the hormone will be absorbed in your blood and transported to your brains. The hormone will activate a switch (compare it to a light switch). As soon as this happens you'll start feeling hungry and you'll want to eat (especially sweet and unhealthy things).
& #x200B;
What makes your stomach rumble:
& #x200B;
This sounds is caused by your stomach and intestines making powerfull movements to knead the food and move it forward. The food in your stomach and intestines is used as a type of 'sounds isolation'. So due to the food in your intestines and stomach you mostly don't hear the sounds of your stomach rumbling. When there's no food in your stomach, the sounds will not be stopped and you'll be able to hear them better. If you have a little brother or sister, try to put your ear on his/her stomach and you'll most likely be able to hear his intestines. This sounds is the same sound the doctor will listen to with his stethoscope.
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46f378ff-cf30-4cb0-8f68-f24e552cadb6
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bvh8y3
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Why are hotel sheets and quilts always white, knowing it is the easiest to stain?
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You can bleach them. It makes it more sanitary for something that's going to be used by multiple guests. Also, visible stains make it easy to identify a sheet that needs to be replaced.
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3c886923-aa7f-4801-a8a7-e24012531d0a
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bvhar8
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Joules are often explained in Newtowns. What do both of those mean?
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"Force" is just a push or a pull. Force is measured in newtons. One newton is roughly the force you need to lift a bar of soap.
But just because you push on something doesn't mean it'll actually move. Applying a force to an object as it moves will "do work" on it, and change its "energy". Work and energy are measured in Joules, and one Joule is one newton times one meter -- it's roughly how much work you have to do to lift a bar of soap to waist height.
Energy comes in many forms: pushing on an object may increase its speed, or lift it up in the air, or heat it up, etc. Energy is a useful idea because it's "conserved": energy can change from one form to another, but the total amount stays the same.
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67ac657f-6d5e-47d9-b917-f6ae77f8d60f
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bvhcz0
|
some physics questions?
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> How is there a 'universal speed limit'? As in how is it possible that you can only move up to a certain speed in the universe ? Is it because there just isn't enough energy in the universe to do so?
As you travel faster your mass increases (there is also some weird things with distances and time and length contractions but that is beyond the scope of this)... As your mass increases the energy required to make you go faster increases. As your velocity approaches ```c``` (the speed of light) the energy required to accelerate you approaches infinity.
> What is gravity? Why are objects attracted to each other? I know there are gravity waves but what causes them?? And why do objects move towards gravity waves?
This is going beyond ELI5. Gravity is curved space-time, as you move through curved space time you distort space-time which will effect how you move through space-time, this can cause your motion to do things like curve or accelerate... All gravity is is an acceleration caused by distorted space-time based on current models... This is my most ELI5 that is hella simplified.
> How does space expand? Scientists say objects are moving faster than the speed of light from each other because the space in between is expanding. What does that even mean??
We don't know. What we know is that most matter in the universe is redshifted to us meaning we are getting further and further apart, however things are getting more and more red shifted meaning it's gaining distance faster and faster. We don't know what drives the expansion or why it does it, so we created a hypothesis and called it dark energy and found out how much dark energy would be required to create the predicted results (something like 76% of the energy in the universe or something like that... I'm not a cosmologist or an astronomer). So afaik we don't know.
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76c84472-f9ea-42d9-b3e4-d2a39cf0b0b1
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bvhef8
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Is vegan prepared foods made by for-profit companies like BeyondBeef and Impossible Burgers healthy or just tasty?
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"healthy" is a pretty ambiguous term. You'd have to look at the nutritional information and make your own decision.
_URL_0_
They have the nutrition facts on their web site.
Beef patties have 47mg of cholesterol as opposed to none in the Beyond Burger patty, and have some more carbohydrates in them than the Beyond Burger patties. Meanwhile, Beyond Burger patties have more iron and phosorus, but less calcium, magnesium and vitamin B-6.
They have comparable amounts of fat and sodium.
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d5f778fe-5bbb-477d-855e-5ed6968b3367
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bvhh2m
|
What does "cultural safe space" and "cultural capability" even mean?
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As I understand it — It’s not just about “not being a d***” — it’s about recognizing that people come from different cultures, different backgrounds and that colors their perspectives. It’s about learning about those cultures in order to understand the context and where someone else may be coming from.
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f24341da-b659-412e-b9ee-ceb80940ffb3
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bvhldh
|
What are electromagnetic waves made out of?
|
Electromagnetic waves are vibrations in the electric and magnetic fields.
"OK, so what are the electric and magnetic fields?"
They're the way we describe electric and magnetic forces.
"Sure, but what *are* they?"
Hey look over there! I thought I saw a birdie! \*runs away\*
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b6345a52-abe8-4e38-96f3-f74e8126f45c
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bvhwjd
|
Why are humans so weak (pound for pound) compared to many other animals?
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That's a GREAT question! Humans seem really really stupid by comparison to animals like cheetahs or gorillas or... well basically every other animal, right? But at the same time, humans have been around for a really long time - something like 3 million years! - so we must be doing something right. But we don't have armor, we don't have speed, we don't have claws...so what is it that makes us special?
Well there are a few theories out there, but my personal favorite is the "running man" theory. Humans have really, really big brains by comparison to other animals. And our brains are super complicated. It takes a LOT of food and energy to feed a brain like that. So we needed a way to get a lot of food - more food than most other animals get to eat. The "running man" theory basically says that humans evolved to run - not super fast like a cheetah - but to run super *far*.
By standing tall instead of crawling on all-fours like a cheetah, humans can get way more oxygen in their lungs. By having lean, long muscles instead of big bulky ones like a gorilla, we're able to weigh a lot less, meaning we need to use less energy to run. And by shedding our fur and evolving the ability to sweat, we can cool our bodies down *while* we're running. This one is *super* important because all other animals with fur on their bodies can't cool down and run at the same time. At a certain point, their bodies get too hot and they have a choice - keep running and die or stop and cool down. But not humans! Humans can run for hundreds and hundreds of miles without stopping because we can sweat.
So to answer your question, the reason why humans are so weak compared to other animals is because we have big brains that need lots of food and the best way to get that food was to have bodies that could out-run all other animals.
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0971dc53-904c-4996-8bad-48bd01e597c8
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bvig0h
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Why can my laptop pick up my WiFi very well, but my phone, on the same desk, hardly connect at all?
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I would only assume better hardware in the laptop given its increased form factor.
Same reason you won't get a core i9 and 32gb ram in a smartphone.
Edit - forgot to add phones are more power conscious so reduce performance of areas to prolong life.
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5effb5c2-0961-49d1-a2dd-eeaf3fb3fdfc
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bvihac
|
why is music so much louder than voices in movies?
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Those films are made to be played in theatres where there are multiple speakers with surround sound. Speaking, sound effects and music can be from separate speakers, so one doesn't overpower the others. Even tv's hooked up to surround sound are in a small space, so the sounds will blend in more with each other than in a theatre.
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cfeb4dcc-d3fb-41a2-b9ea-8b8437e1ca19
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bvijsz
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How does the keto diet work?
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Your body relies on different types of sugar to do most of the stuff necessary to keep you alive. The easiest way for your body to get those sugars is through carbohydrates like bread, potatoes and sweets. You store the extra as fat, which your body can also convert into sugar if it has to, but if there are carbohydrates available it'll use those first. The idea behind a keto diet is that by not eating sugar and starches, you're forcing your body to burn off it's fat reserves.
Macros refer to macronutrients, the three main categories of food. Protein like meat or beans, used to build and maintain muscle, carbohydrates like sugar, rice, wheat or potatoes which provide quick access to energy and fats like butter or oils which can help distribute nutrients through the body and act as a kind of storage system for energy like I mentioned.
There's no single perfect way to eat since your diet depends on your goals. A marathon runner wants a lot of carbohydrates and might even have a hard time keeping weight on while someone trying to gain muscle will want to make sure to get a lot of protein after working out.
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3f3239e8-9614-4f77-bb97-09ba2cdd34bd
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bviuti
|
Why do some countries have differently shaped electrical outlets/adapters?
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Most countries developed their own standards when electricity started being used. Some were better than others, and some decided to take the better ideas and combine them.
There would be a bit of protectionism involved as well. You don't want someone buying an American product when they could buy manufactured right here in France, or vice versa. Travel was also a lot more difficult back then as well. Finally those that were travelling were not carrying a lot of electrical devices with them.
After these systems were developed, it's much harder to go back and change them.
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2898c662-f55b-4bf4-bdb5-41a691f29117
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bviw04
|
Why do escalator handrails never run at the same speed as the escalator itself does?
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As Don-Slade has already kind of pointed out (at least in Germany) escalator handrails have to run a certain percentage faster than the escalators itself to pull your point of weight forward. By being just slightly faster, when you grab a hold of them, your weight will be distributed more to the front, thusly reducing the risk of you falling backwards down the escalator.
Likewise, when you’re going downwards, the handrails tend to run a bit slower to pull your weight back so you don’t fall down.
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ca739426-77d1-4fbd-ab78-82bcc0f818e0
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bvixyp
|
What exactly causes Motion Sickness?Is this-a united mischief of Physics and Biology,treatable?
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Motion sickness appears when your center of balance control (your inner ear) and your eyes receive conflicting informations. For example, if you read in a car, your eyes don’t see that you move, but your inner ear can actually feel the car moving with you inside. Same thing for boats.
As for why you will want to vomit, there is an hypothesis : your brain could actually believe that this conflict of information happens because you are poisoned and hallucinating. So it would make you vomit to get rid of the poison. But then again, it’s an hypothesis.
It can be treated, there are drugs that you can take before a travel to avoid motion sickness, but if it’s already too late, focusing on the road ahead will rebalance the informations.
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e0db22b5-6758-4cc6-a9c8-4e3fb8c766e6
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bviyl2
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mobile chat app
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Naw you're good. Anyone who says that they are tracing your IP is just using it as a scare tactic. If they had the knowledge to do so they most likely wouldn't be telling you they were doing it.
Its kinda like those phone scams where they pretend to be the government and scare you in to paying with an itunes card or what not. They basically just prey on fear to try and get you to do something.
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48df9b62-3310-4d29-9a36-fe1303faeea7
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bviz4h
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how can the universe be expanding, when it is growing in to space that already exists? Isn't that just discovery over expansion?
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What we are talking about when we say that the universe is expanding is not that the matter in the universe moves outwards or that we can see further. However the fabric of spacetime itself is expanding. Imagine that you have a granite slate kitchentop. The granite is very solid. Lets say you have a big kitchen machine that you use once a year. And you have issues with in moving around when you use it. So you drill some holes in the granite top and bolt the machine to the granite. The next year you get your machine and put it over the holes only to discover that the holes does not fit any more. The distance between the holes are larger. And if you measure your entire kitchen top you see that it have become larger. Even though the granite it feels heavy and solid it apparently have stretched and expanded over the year. You now have more granite then last year and you have no idea where it came from.
& #x200B;
The universe is the same. Space itself feels very solid. But if you measure it carefully there just seams to be further and further between fixed points over time. Apparently space just appears everywhere making the universe expand. The space did not exist before but now suddenly it is there in the middle of everything.
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e5c19d65-341e-46b8-a211-6dccdbd18dc7
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bvj3fb
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Why do exams have pages that say 'blank page do not write' or 'page left intentionally blank?'
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It's so the test taker knows that they are not missing a page. In any automated system there is the possibility of something going wrong, even printing.
One of the first things you should do for any test is to go through the questions first and make sure no numbers are skipped. Mostly between the pages. So first page ends on question 4, second page should start with question 5.
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7085df9c-df91-4195-997e-a0dd442ffa75
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bvjagx
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how are some animals like squid and chameleons able to change their color?
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for squids :
they have cells in their skin that can expand and contract to expose another layer of pigmented cells
they also have cells in their skin that can reflect light in different ways by iridescence
all of this combined allows them to shift their hue and texture
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ee916f03-4f01-4bdb-bd3b-cf24ed3d872e
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bvjfnt
|
Where is the line between criticising Israel and being antisemitic?
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Antisemitism is negative treatment of someone purely for their jewish etnicity.
Criticising Israel or specific jews can be perfectly valid - if for good reasons. The etnicity someone is born with is not a good reason.
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a5af2ba6-1566-4738-ace8-c3b1536ef83c
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bvjham
|
How is radioactivity spread/contaminating anything that it comes into contact with?
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Often people misuse the words “radiation” and “radioactive contamination”.
*Radiation* refers to energetic subatomic particles or light that is emitted from an atom. This includes alpha particles and beta particles (both subatomic sized) as well as gamma rays. *Radiation* is emitted in a straight line and causes chemical reactions in objects that it hits, but it does not make other things radioactive.
*Radioactive contamination* refers to small pieces of radioactive material. Each piece of contamination (which can be large pieces, dust sized, or even smaller) contains millions of atoms that individually emit radiation. Like regular dust or dirt, contamination can be spread around by surface contact or in an airborne fashion.
At Chernobyl, the reactor was severely damaged and caught fire. The fire spread large amounts of *contamination* (individual pieces of highly radioactive material) into the local area and the atmosphere.
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859f2b53-c0d2-4bc9-882b-3ac1af75e298
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bvjjbh
|
Why cannot there ever be a successful breeding between a human being and another animal?
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Huge over simplification; when you make a baby, its DNA comes equally from the mom and the dad. The DNA is a big set of building instructions, and a playbook of how to react to situations. For humans, we get every odd page from Mom, and even pages from Dad. Most of the time, the instructions still make sense. Chimeras, like mules, ligers, and tilons have building instructions close enough that it doesn't die instantly.
Imagine trying to assemble an F35, if the guide book has the instructions for an F16 in English in the evens, and an s300 in Swahili on the odd pages.
You might get somewhere, but will it fly?
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75499bfb-b932-44d9-8b91-3aa9083e3c25
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bvjqn0
|
Why is it we see the moon at daytime occasionally?
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The Moon does not stay on the side of the Earth opposite the Sun. It orbits the Earth, making a complete circle every 28 days. This means that it spends half its time on the same side of Earth as the Sun, making it visible for at least part of the daytime.
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3375e77f-5310-4db0-8aed-240ac392063f
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bvjzlk
|
What do those short metal cored cylinders do for USB cables?
|
They are what is known as "ferrite chokes". When there is a fast-rising spike in electricity, often caused by static electricity, the spike generates magnetism in the ferrite core, before it enters the device and caused errors.
The core cannot absorb the energy of a large spike, however. For that you need input protection diodes. It just "takes the edge off it", making the spike more rounded, less abrupt, which means that it doesn't create electric noise inside the device.
Input protection in devices had got much better lately, so the chokes are generally only seen on older cables, or very sensitive or safety critical devices such as medical equipment.
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ea2d8bb3-0b62-4d3d-9164-074e312d2649
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bvk0ee
|
How can medicine work so quickly if the digestion process takes a long time?
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Some drugs are absorbed into the blood stream through the stomach lining while others are absorbed into the blood stream in the intestines. I believe that if it's an acidic drug it absorbs in the stomach and alkaline absorbs in the intestine. The liver receives the drug through the blood stream so the quicker it gets to the blood, the quicker the liver gets it.
The contents of the stomach are constantly churning and fast acting drugs are designed to dissolve fast. I would venture to guess that your drugs are acidic and absorbed through the stomach lining. Since stomach contents are always moving, it doesnt have to fight your food to get where its going.
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705152ad-f69d-4c28-b8ee-48ff32165080
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bvk6lt
|
In trading, what does liquidity mean and how does it work
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You can think of it as the 'transferability' of a financial instrument (either cash, or an investment). High liquidity means it's easier to use and transfer an item; low liquidity means you're pretty much stuck with it.
Cash is a very liquid thing. You don't need to find a buyer before you can use it, or involve a middle man. You can just go out and spend it. If all of your wealth is tied up in housing, for example, that's not very liquid. If you can't find a buyer, you're technically *worth* a lot, but if a hot new investment opportunity opens up, you're probably not going to be able to get enough cash together quickly to invest in it.
Similarly, if there's an investment that is constantly changing hands -- Bank of America stock, as /u/Bhimpele said -- then it's considered liquid; it moves around the marketplace a lot. If you have a stock that very few people are interested in buying or selling (and it can be either, not both), it's not liquid. It's either very hard to take possession of it, or if you've got it it's a pain in the ass to get rid of -- therefore it's not easily transferable.
It's liquid because it flows easily from one place to another.
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2fdb31dd-94ca-4789-9d4c-1687f9639450
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bvk75u
|
LNG gas process?
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Natural gas is formed under the earth from the remnants of plants. These gases are pumped from the earth but contain a lot of impurities. It goes to a complex process that removes the impurities and is then cooled to liquid form where it is transported for use.
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6ebf2f55-86eb-4c43-a186-4cbda7fad7d8
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bvkbw6
|
The 80/20 rule
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It’s a rule of thumb that can be applied to a number of fields. I can give you the application of this rule, also called the Pareto Principle, to the field of process improvement. You can then figure it out for your context as a homework assignment.
It all starts in Italy in the early 20th century (or late 19th century), where Pareto, an economist, calculates that 80% of all land in Italy is owned by 20% of the population. Since then, people use that example to state that when you have multiple causes bringing about an effect, 80% of the effect is caused by 20% of the possible causes.
An example from process improvement: let’s say you manage an assembly line. Each year, there are hundreds of defects being produced, and it’s your job to reduce that number. You take a look at the data: hundreds of defects, and multiple causes attributed to them. Which “cause” do you tackle first? Which problem do you fix to give you the biggest impact on quality? This is where the 80/20 rule comes in. You run through the defect data and you tally how many defects were due to each possible cause. What you generally find is that a small amount of causes (the “20%”) are triggering a large amount of defects (the “80%”). So you go after those 20% to give you the biggest bang for your buck.
Is it always 20% and 80%? No. It’s just that 80/20 is a nice mnemonic to remember.
You can totally apply this to any other field. 20% of employees account for 80% of sick days. 20% of menu items account for 80% of daily sales. 20% of clowns account for 80% of clown-related crime.
Hope this helps!
Edit: those damn, pesky silent letters!
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ab1c03e5-e5a4-447f-a1e9-947aa1d4d476
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bvkd8z
|
What’s the biological significance of puppies having “puppy coats”? And why do their patterns have to change once they’ve reached maturity?
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Perhaps it is like camouflage, just like in baby deer (that have spots) that disappear when they mature. Nature is pretty cool.
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895c07f4-c3ad-4465-8907-65533686a430
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bvkfas
|
Why is there significantly less space debris over the north and south poles?
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It takes a lot of energy to change an orbit to go over the poles, and such an orbit won't be geo-stationary (stay over the same spot on earth.) Many types of satellites need a stationary orbit to function, so those orbits (generally near the equator) will be more popular. An orbit over the poles would be useful as it would cover the entire earth over a period of time, but it would be costly to attain and not suitable for use as a communication satellite.
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9ff69eb8-3603-4edc-8f48-16268df574e4
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bvkoqo
|
I know humans can't digest corn cellulose but how exactly corn survives hydrochloric acid?
|
So typically the issue is not the exposure to acid. The corn is immersed in as much digestive acids as anything else you eat, however different food substances will be affected and digested and broken down at different rates of speed, your digestive track however is pretty much always working at about the same speed unless you're sick or something, so the corn typically doesn't have enough time to fully break down.
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403768e4-04d0-4023-9d26-9a841fa4df4b
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bvku95
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Why do our eyes burn/sting when something gets in them?
|
The eyes are one of, if not the most sensitive part of the body, it's simply them getting irritated.
Just like a corrosive substance will irritate your skin, the eyes are so sensitive that dust, smoke or even an eyelash will cause pain. Because they are so important, we evolved with super sensible eyes to protect them.
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e08f998c-7458-4840-b0ab-4db04c28813c
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bvl0cj
|
How does an internet search work? Do they get slower for each new internet page created or are there mecanisms to avoid that?
|
The search engine couldn't search all websites each time someone puts in a search word. Instead, it creates a list of all words or phrases it finds on every webpage, and next to each word it writes down the links to every webpage containing that word. Now if someone puts in a search term, the search engine can simply check its list and immediately give you your search results. Such a list is called an index. The search engine will visit all websites on a regular basis in order to see if something's changed. This is called crawling.
Does internet search get slower for each new internet page? Well, updating the index will take longer each time a new website is created. Looking up something in the index will also take longer if the index gets bigger. However, servers get faster and faster, and database systems probably keep getting more efficient. So I doubt this would be noticeable.
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5ae43390-a222-4e05-bbe0-43a9f7e3917f
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bvl1xj
|
How does an atomic clock work?
|
TL:DR Atoms vibrate regularly and this vibration is measured and converted into vibrations per second and thus seconds.
First, think of what a clock actually is. A measure of a time period.
On original pendulum clocks this time period was kept relatively constant by something called "Simple Harmonic Motion" (something swinging backwards and forwards) which basically states that for a string (or pendulum) in this case with a fixed mass at the end of it the time period of its oscillation (how long it takes to go swing then return to its original position) will be constant.
The actual equation is T = 2 **π \* root**(l/g)
Where l = length of pendulum and g = gravitational field strength (earth = 9.81)
But as you can see if we know the time period we want which is 2 seconds (remember that each "half swing" is one full second on a clock) we can work out exactly the length of the pendulum we need to produce it hence why lots of grandfather clocks are all similar in size. This is obviously helped along by electricity but that's the premise of a clock modern clocks just use stuff like the frequency of electrical signals etc to keep that steady period.
& #x200B;
So now we should have a fair outlook on what an atomic clock has to do. Find something that is regular in frequency.
Frequency is actually just 1/T so if a grandfather clock had a time period (there and back) of 2 seconds its frequency is just 0.5Hz or 1/2Hz.
& #x200B;
Now comes the "atomic" stuff:
Atoms are constantly absorbing energy from lots of sources but mainly from EM waves. When an atom absorbs these waves lots of things can happen including excitation of electrons which can then release that energy at lower states.
But for an ELI5 it really doesn't matter what does matter is that atoms of everything are in a constant state of movement, vibration and "resonance" which in itself has a set Time period and frequency of oscillation.
What makes this amazing for timekeeping is that any single atom of one isotope of an element or ion will resonate at the exact same frequency as the next making it super convenient for timekeeping as these oscillations could happen here or on venus and it would never change.
Therefore by using a method to find how quickly they resonate you can then find how many oscillations are in 1 second and match your clocks accordingly.
& #x200B;
In the real world, the isotope used is Caesium-133 which has 9,192,631,770 oscillations in a second.
You see the level of precision now? This means that atomic clocks are accurate down to 1x10^(-9) seconds.
& #x200B;
Real definition of a second: “The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. This definition refers to a caesium atom at rest at a temperature of 0 Kelvin.”
##
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ea9efd18-5e0d-463e-aca0-fd18929972dd
|
bvl5h4
|
Why do you sometimes simply 'feel' that somebody is looking at you?
|
[_URL_4_](_URL_4_)
> Humans are sensitive to the gaze of others. When another person changes the direction of their attention, we automatically follow their gaze. It's more than just being predators, who as a group are naturally sensitive and drawn toward changes in the environment. It also has to do with the cooperative and social nature of humans and how we've depended on one another throughout our history and development.
>
> Another reason, if you look at human eyes in contrast to other animals, the sclera or white part surrounding the pupil is far larger. In most other species, the pupil takes up most of the eye. This is to obscure their eyes from predators. But for humans, a larger sclera allows us to notice the direction of each other's gaze quickly.
>
> Of course, we don't have to be looking directly at someone to tell whether or not they're staring at us. We can also evaluate the direction of their attention through our peripheral vision. But this method is much less accurate. A pair of studies finds that we can only accurately detect whether or not someone is staring at us within four degrees of our [“central fixation point."](_URL_1_)
>
> It isn't always about seeing another's eyes. With our peripheral vision, we consider the position of their head. And other clues such as how their body is positioned lend to whether we think they're looking at us or not. What if we're not sure? Just to be safe, [the brain errs on the side of caution](_URL_0_). It assumes we're being stared at, if there's any doubt.
>
> So what about when we feel someone staring from behind? According to a 2013 study published in the journal [*Current Biology*](_URL_2_), that's just a fail-safe. Humans are [hardwired ](_URL_3_)to think that someone is starting at us when we can't see them, even if we have no evidence to suggest so.
>
> Psychology Professor Colin Clifford of the University of Sydney's Vision Centre, found that when people can't tell where a person is looking, they automatically assume they're looking at them. “A direct gaze can signal dominance or a threat, and if you perceive something as a threat, you would not want to miss it," he said. “So simply assuming another person is looking at you may be the safest strategy."
TL;DR: We have hardwired systems in our brain that enable us to detect when someone is staring at us due to our ability to easily recognize another person's eyes, even through peripheral vision. Sometimes, we may feel that someone is staring at us even if we can't even see them, this is a hardwired instinct designed to protect us from predators.
|
0bc93192-8f32-40c7-a869-a144e49b0632
|
bvl8ju
|
Why do stinging nettles hurt so much and what do they do to you?
|
The leaves themselves have small almost invisible "spikes" or stings on the surface of them. These are coated in methanoic (formic) acid which is what actually hurts. The acid itself is actually extremely similar to vinegar so you should get a similar feeling pouring vinegar into dot sized cut :D
|
690fcc6a-c397-44d4-9ce9-73f4a88236f1
|
bvl8tx
|
what is autism exactly???
|
Shortly put, autism occurs due to the brain functioning in a different way. For some, this can be a barely notable "different" air about them while others are not very functional due to a brain that cannot function as most other's do.
It is a spectrum, meaning "autism" has many severities and even comes under different names for different severities or depending on how it impacts someone's life.
This can, of course, lead to loneliness yes as many on the spectrum have trouble connecting with people. They can be very socially awkward and even a little cold and logical at times depending on who it is and what flavor they have.
Even shorter put: Autism is considered a developmental disorder of the brain that can have symptoms ranging from being a little awkward and high functioning to being unable to care for yourself and basically trapped in your own body as if it were a malfunctioning robot with you inside trying to pilot it.
|
31f9ffab-5f53-477a-a1af-95c910eef265
|
bvm4m7
|
Why is it that I've felt really tired for the first 15 hours of my day and now at 1:00AM I suddenly feel wide awake?
|
Because your sleep schedule is fucked, bro. You're forcing yourself to stay awake, and the body eventually tries to accommodate that, but the fact remains that you need sleep.
It's possible to desperately need sleep and "feel wide awake" at the same time.
|
3cc27f7f-8128-4cef-a305-8760bbba857f
|
bvma2n
|
How do smokers' lungs get used to smoke, and can they then handle inhaling all smoke (e.g. fire)?
|
The lungs don't get used to the smoke, it's just that there's not a very high concentration of smoke from the cigarette when you breathe in. The bigger thing is that your body recognizes the ash particles / the smoke when you try to breathe it in, and that can force you to cough the first few times, but eventually you get over that.
> and can they then handle inhaling all smoke (e.g. fire)?
Absolutely not. Cigar smoke is very thick and can cause a person to choke hard, and smoke from regular fires is also very thick.
|
f906e08a-ee0f-405c-93ef-1cc49e8fc7e0
|
bvmfbk
|
how do you figure out the elevation of a city?
|
These days, you use a GPS. You have satellites that know exactly where they are in space, and those satellites are constantly "shouting" their exact position and time. Your GPS receiver can then find several (usually three) satellites at a time, and see how long it took for signal from all of them to reach the receiver, and do some math to find exact latitude, longitude, and elevation.
In the early days, before satellites, this was done by surveying. First, you would measure the horizontal position from some reference point, and them measure the angle up from that reference point. From there, you can make a triangle and know the height. This requires that you be able to see your target from your reference point. For things close to the ocean, that reference point would usually be the ocean, but further inland, you would often have long chains of reference points - measure one, use it to find the next, so on.
If you go hiking, at least in the US, you'll sometimes see little metal disks in the tops of hills and mountains that look something like [this](_URL_0_) in the ground. These are survey markers, meaning these are points where the position and elevation have been precisely measured, and so can be used to find the position and elevation of other things in the area. They're usually at the tops of hills, because most old surveying methods needed to be able to see the point being measured from the reference point.
|
a0ea5296-0601-4d52-9c7a-9c07aedc8d69
|
bvmfbr
|
How/Why is the animation in the Spongebob movies different from the TV show?
|
This happens with all cartoons that are made into movies if you watch The Simpsons Movie you'll also notice this it's mostly because they have a better budget, a bigger one.. to work with for a movie, because unlike television, the movie makes more money.
|
08f059cb-7946-4945-ba69-bf9049d64e5d
|
bvmhnm
|
How are some traits heritable?
|
So genes are what makes something heritable, you get one set from each parent and for some characteristics there is a single dominant gene and a single recessive one meaning you express only one gene from one parent.
However for a lot of characteristics there are many different genes all contributing to that one characteristic, some may act against each other and some may act with each other, and some may be 'codominant', meaning both sets from each parent are expressed.
So for skin tone, there are many genes contributing and some are codominant, meaning there can be a variety of skin tones even if your parents have vastly different or very similar tones. (of course not including tan and other environmental factors)
For eyes, there are actually so many genes that it is possible for anyone to have any colour eyes, regardless of their parents eye colour (though the probability obviously is very low for rarer colours like green, grey and Amber)
Hope this answers your question, please feel free to further query in the comments or by message
|
c773e62d-40b8-4cf3-ad78-f8cb197d5660
|
bvmj2r
|
What is the 'prozac myth', why is it so controversial and what do we know about the effect of drugs like prozac on people perception of reality?
|
I think the prozac myth is around studies on the efficacy of prozac vs placebos.
Re: perceptions of reality. It's important to remember that depression changes people's perception of reality. I don't think the drugs change the person's perception of reality, but rather they are supposed to level the good chemicals in your brain to help you feel more like yourself and to give you the energy to deal with the depression/OCD/other issue... which lends itself to healthier mental health including how you see life.
Of course in the same way different drugs will work for different people there might be people who do experience different perceptions of reality on them. But it's difficult to say - how long did they have depression? Was their original perception of life accurate or just so long standing it became 'normal'? Are they on other meds, interacting substances or have other issues that are creating this side effect?
On a side note, Prozac Nation is a memoir of a woman who started taking prozac when it was quite new. Very interesting read.
Edit: making point clearer.
|
de5cd944-6004-4ad4-8dfc-9912ffcaf477
|
bvmm8d
|
why does being obese feel so light
|
Because when the fat is inside you, it's more evenly distributed around your body rather than being in one place. And because you become accustomed to it.
|
fc53d6a9-200d-4384-b17a-798099dd6b4e
|
bvmom4
|
What is screaming?
|
Its a warning call. Language is a relatively recent evolution in humans, having only appeared around a million years ago. Warning calls are a much older and more deeply ingrained process in nearly all social land animals. Simply making a loud noise of a particular pitch and pattern that lets everyone around know something is wrong.
Children are more likely to do so both because they're generally vulnerable and need to alert others to help them in case of danger, and because they are inexperienced and haven't learned what qualifies as danger yet.
|
aa65e353-a92e-498b-a62e-0fbf2b0a4dff
|
bvmz69
|
How did people start measuring distance at sea where it's water all around?
|
Speed of ship and stars. Drop a buoy in the water from the front and count the time it takes to get to aft. That gives you the knots or speed. Do that every so often and navigate by stars. Wasn't accurate like gps but it worked well enough at the time. Also ocean currents weren't really known of back then.
|
c0769b8e-a356-4ce7-b27a-dfc9ada51ad5
|
bvngus
|
At low tide, where does the receding water physically go?
|
To the area where the tide is high.
|
c822139a-0f24-44f3-942b-0a8755ad07ab
|
bvnhag
|
Why some animals lie down to sleep and others have no need for that
|
Some animals are able to find a place to hide and sleep (like a burrow or den). Others are big enough to not worry about most predators.
Animals like birds, dolphins or whales let half their brain sleep. The rest of the brain keeps going, then the parts of the brain sleep wake up and the other parts go to sleep.
|
7c27e2dc-776f-4e28-aef1-a324e99b3ca9
|
bvnmcy
|
How does the body rid of heavy metals?
|
The body *doesn't get rid of them* and that's the problem.
They cause all kinds of problems because they're poisonous, and the body has no way to get rid of them, so they accumulate in your tissues until you die.
|
d7be46d1-6364-4fea-8e79-7c9991a5e0ee
|
bvo7ew
|
Why is the majority of the Earth's landmass in the northern hemisphere?
|
It's mostly a coincidence. Same reason a majority of the land is bunched together on the same side of the globe. The pacific ocean is almost half of the earth's surface area, but it's tough to see on a normal map since that's where it's cut.
|
0fd29189-2d4a-4ffc-a2df-1fcb4aaf2e9b
|
bvofxi
|
Why do saying or writing our thoughts out can help relieve stress?
|
Once you express a thought, the brain “checks it off the list,” considering it a done deal even if you don't actually act on the thought you express. This is also why you might feel less motivated toward a goal after telling someone about it.
|
c77fc6d7-4233-41af-8f84-d419a9fcf96b
|
bvok5h
|
What is 'Total Football' actually? And Why was it so effective for the Dutch?
|
Essentially, it means that any outfield player in a team can play in any of the outfield positions. This means that a player with the ball can head forward and attack the opposition, and a team mate can fill in behind them, retaining the structure of the team set up. It was popularised by the Dutch national side in the early 70’s, who featured everyone’s favourite football Jedi, Johan Cruyff.
|
a91cf4ff-6c8e-422b-8dab-d099158c2ccc
|
bvox04
|
How do mathematicians measure pi to over 200 million digits?
|
It's calculated by supercomputers. There's a few infinite series such as the Gregory Leibniz series that can be used to calculate the exact value. The current record is 31.4 trillion digits, calculated by Google on this π day
|
a7d8ed79-dc57-4ec4-bca5-97af5f755460
|
bvozap
|
When the doctor/nurse takes blood from you, why do they try to find a vein, not an artery? And also why is this mainly done on the arm as opposed to other parts of the body?
|
They use your arm because it is easy and convenient to get at.
They use veins because they don't want to kill you.
|
c8f2f5d1-f473-45c1-a1a8-cb4a4f8e8fa8
|
bvpb2m
|
Roe v Wade concluded that the right to abortion follows from the right to privacy. What was the reasoning behind this?
|
A lot of people don't understand Roe v. Wade. There is no such thing as a "right to privacy" - rather, that phrase is just an easy way of explaining the limitations of the government's police power.
In the US governments don't have any power by default. In order to do anything, a government needs to be able to point to a constitutional provision that explicitly grants them that power. For example, if the government wants to outlaw theft then it has to have some constitutional provision that gives it the right to do that. In the case of theft (and most other criminal laws) that power is the police power.
Every state level constitution has a clause granting that state government the right to regulate the "health, safety, and well being" of the citizens of that state. We call this phrase the "police power" and it grants state governments wide ranging power to regulate your personal life. But an important limitation of the police power is that it only allows the government to pass regulations that increase the health, safety, or well being of society. If someone's personal actions don't affect society, then the police power does not grant the government the right to regulate them.
Roe v. Wade was not about establishing a right to privacy. Roe v. Wade established when a fetus becomes a legal human being. Before a fetus is a legal human being, it is legally no different than a tumor and the government has no more right to regulate a medical procedure to remove it than it would to regulate a medical procedure to remove cancer.
However, once a fetus becomes a legal human being, then harming it causes harm to society and the government is free to regulate such harm (IE, by outlawing abortion).
This is where you get the "right to privacy" from - its very, *very* difficult to make an argument that actions which only affect consenting adults are harming society. Therefore, the police power does not grant the government the right to regulate such actions.
But the right to privacy isn't a right like the 1st Amendment. The 1st Amendment grants you a personal right to free speech. The government can overcome that right in certain instances, but its very difficult to do and requires the government to have some overwhelming need to do so.
The right to privacy is not a personal right - its a *lack* of a right to do something on the part of the government. This means that it is much easier to overcome. What constitutes a harm to society changes over time. For example, only a handful of the most extreme people who are opposed to gay marriage actually believe that gay sex causes any harm to society, and as a result gay sex is modernly protected by the right to privacy.
But that wasn't always the case - for most of US history most people legitimately believed that homosexuality was a virulent plague that destroyed lives and could spread - similar to how society views drug use today. Much in the way that drug use today is not protected by the right to privacy, gay sex was not protected by the right to privacy until 2003.
People tend to think of rights as a one way street - that your ability to act without government regulation is constantly increasing. But this isn't true historically - society's views on what constitute a societal harm are constantly shifting, and the right to privacy is only as strong as society believes it to be.
|
109346ef-6a93-4f02-948c-d34011820efe
|
bvpg1u
|
what is special about sex that makes it possible for some diseases to only be sexually transmitted?
|
It's the transfer of fluids mixed with mucus membrane in the genitals.
Anal is extra receptive to transfer due to the high absorbancy in the skin wall.
|
470bac4b-d248-44d7-8b0e-2114432552fb
|
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