question
stringlengths 19
300
| answer
stringlengths 31
1.02k
| negative_1
stringlengths 31
1.02k
|
|---|---|---|
What's the difference between my 2.4 ghz wifi connection and my 5 ghz connection?
|
Basically everything wireless we use is on a 2.4 ghz frequency. Bluetooth headsets, baby monitors, phones, garage door openers, etc. Basically it's he industry standard as to not interfere with other radio frequencies that are flying around your house. With a 5 ghz wifi connection, you get away from the congestion of all the 2.4 ghz waves that may be interfering with each other. This can lead to better connection and faster download speeds.
|
Basically there is no functional difference between the two, either way you in theory get the same thing. However, in practice at 5ghz you should get a lot less interference from other devices. Most Wifi Routers work on 2.4 ghz. Bluetooth devices work at 2.4ghz. Wireless mouse/keyboards work at 2.4 ghz. Basically 5ghz is not better because it is 5ghz. It is better because it is not 2.4 ghz.
|
Why can't astronomers say with certainty if a specific asteroid will or won't strike the earth?
|
Because of the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, asteroid belt, Kuiper Belt, and Oort cloud. Most people assume that asteroids go in a straight line. But what many of us forget is that the gravity of nearby planets affect the trajectory of an asteroid. Even a pull of a body as small as the Moon can drastically affect the direction and speed an asteroid is going, even if it's on the other side of the solar system! Also, nearby stars also have a minuscule, but still measurable, gravitational effect. These effects might only pull an asteroid a couple millimeters in another direction, but over time, these changes add up. Humans don't have enough computational power (yet) to try and compute all these different unknowns. Trying to predict the direction of an asteroid is known as the [N-Body problem](_URL_0_).
|
Asteroids are in orbit around the sun. Orbital velocities are high. Earth is moving at 30km/s around the sun. Asteroids have similar orbital speeds. But if they cross Earth's orbit their velocity won't be aligned with Earths velocity. The velocity difference can then be very large. Asteroids can only collide with Earth if they cross Earths orbit, so many asteroids colliding with Earth have high velocities.
|
Why are famous works of art stolen when they can never be sold or displayed?
|
Not a historian, but you can sell and display stolen work, just not legally. There is a massive black marketing for prized artwork that private collectors will buy. If it's a private collection, like in a private residence, then they can display it.
|
Whoever buys them *in a country with honest police forces and international extradition treaties* will never be able to show them. Typically stolen art, exotic cars, and artifacts end up in private collections in slightly less than reputable nations. Yes a billionaire in the US or France can't get away with showing off a dubiously acquired sculpture for very long, but one in Russia or Malaysia can.
|
Object oriented programming?
|
OOP is like thinking of a program as separate 'living' things. A good visualization would be to picture your program as a 'company' and the objects as its 'employees'. Everyone has their own job, interacts with other people and stuff related to your job stay near you. Everyone tends to have just their single responsibility. Dumb example incoming, bear with me. You have the guy who writes the letters (Writer), the guy who licks the stamps (Licker?), and then guy who mails it (Mailer). Everyone has their own desk, with their own tools, and if you need more of them you can hire more (instances) of them with a job description (class).
|
I'd explain better if I wasn't on mobile but here's the really short version. You make classes that have their own specific functionality(objects ). You can build upon objects and extend or inherit from them. The program runs by making all the objects interact. Everything in a program should have it's own object. For example in a game of pong where one paddle is s computer, there will be an object for the paddle you control, the computer paddle, the ball, and depending on How it's done the game area.
|
Why are some flu symptoms vomiting/diarrhea if the flu is a respiratory infection
|
Well, first of all, a lot of what people call the flu is not actually the flu. People talk about the stomach flu, for example, but that is not a form of flu. That said sometimes the flu can cause vomiting in that if your respiratory passages are infected, you produce a lot of mucus. Inevitably, you are gonna end up swallowing some of this mucus. Some people swallow more of it than other and some people get nauseous because they swallow so much mucus.
|
Depending on which bacteria, virus or fungus (or parasite) causes the 'stomach flu' the modes of how vomiting and diarrhea are caused can be somewhat different. Generally though, the diarhea is caused by toxins that affect the intestinal wall membranes' permeability for certain ions causing an imbalance in osmolarity which leads to too much water in the intestines and the vomiting is caused by the irritation of the gastrointestinal walls due to the microorganisms and toxins damaging it.
|
Why do an all electric car needs a 12V battery.
|
Because they don't want to reinvent everything that's already developed for cars. Window motors, headlights, radios, various sensors and every electronic device you can think of that your car needs to run all run off 12v power. There's no reason to redesign a new one of everything when it alread exists just for the sake of it running off the high voltage battery.
|
Because lead acid batteries are cheap. Most of the time when a internal combustion engine runs, it doesn't need a battery. You only need it to get it started. Your alternative is to use a $500+ lithium battery that you only use maybe a few times a day for few seconds Ev's and hybrids use the battery all the time as you're driving. So capacity and weight make up in performance.
|
How are we able to perform a body transplant when we can't repair spinal injuries?
|
Spinal cord injury researcher here. You are absolutely correct, we have no idea how to repair a typical SCI... however, in this case the nerves of both patients are likely fully intact, making it a much easier job than coaxing cells to regrow following an injury. That being said, I agree with u/AHoddy that this is extremely unlikely to work. This is more of an experiment to see what will happen as well as a "last-ditch" attempt to save a terminally ill patient. Also, thank you for calling the procedure by its proper name: a body transplant. It irks me to no end when people call it a head transplant.
|
Once neural tissue is damaged that is it, there is no repairing it. If it was that easy we could simply graft new tissue to fix broken spinal cords
|
What did the US Navy rely upon immediately after WWII to sink enemy ships after the battleships were retired?
|
U.S. Navy doctrine was to fight major "surface" engagements in Carrier Battle Groups. This is a fleet element based on one or more aircraft carriers for offensive strikes and cruisers and destroyers to defend the Carrier. Since a Carrier has a range of hundreds of miles, the main idea of a Carrier Battle Group is to stay at a very long range and sink enemy ships with the Carrier's air group. Cruisers and Destroyers in this period were mostly outfitted with anti-air and anti-submarine weaponry, with most guns being "dual purpose" and also useful against aircraft. Since the Carrier would fight at ranges in the hundreds of miles, the Carrier's escorts anti-surface capability did not need to be extensive.
|
Blackouts along the Atlantic coast were often ignored or flat out refused by cities like New York and Atlantic City. Many freighters and tankers were torpedoed within sight of shore, silhouetted against the city lights. On April 10th, 1942, a tanker was torpedoed off Jacksonville, Florida, and onlookers watched as the U-Boat proceeded to surface and shell the ship in full view of the shore. A general blackout wasn't enforced until August, by which time most shipping had started to run daytime only or joined convoys, and the attacks had mostly ended. Homer Hickam *Torpedo Junction: U-Boat War Off America's East Coast, 1942*
|
What is Exergy in terms of Thermodynamics?
|
Exergy is the energy that an object could transfer to its surroundings. Imagine a warm object in a room. That object has thermomechanical exergy because it is warmer than room temperature. When the object cools, heat transfers from the object into the room until the object is room temperature. Now the object has no exergy from heat, and it is in what is called a dead state. It will never be able to transfer any heat into the room as long as it remains room temperature. While everything has heat and is somewhat warm, exergy is our colloquial definition of hot and cold. When you are cold, you have positive exergy. When you are warm, you have negative exergy. When you are in a comfortable room, you are in a dead state
|
I think it's the second law of thermodynamics, sorry.
|
Why do you feel hot and what causes you to feel hot from embarrassment?
|
Long story short, we have special kinds of nerve cells called thermoreceptors, that send signals to our brain when temperature changes. That's what makes us 'feel' hot. When embarrassed, adrenaline is released which increases your heart rate and metabolism - heat is released as a byproduct of a lot of chemical reactions that go on in our body, and when metabolism is increased, these reactions go faster so release more heat in the same space of time. When heat is released faster than we can get rid of it, we feel warmer.
|
Fight or flight instinct. Whenever you're in a stressful situation (and being embarrassed does count) you start releasing a lot of adrenaline, causing your heart to pump faster, which means increased blood flow. More blood flow means you feel hotter. The increased blood flow is also why you blush when embarrassed.
|
How are atoms "empty"? Chemistry
|
I don't think I entirely understand your reasoning for why there would be anything inside an atom. Think of it this way: You have the nucleus and a statistical distribution of negative charge in a cloud around that. At any given time, the electrons are somewhere and the nucleus is somewhere, and all these particles have finite radii and mass. So, since these particles are not directly touching each other, we can conclude that either something else fills the remaining space between the average radius of the atom and the nucleus, or nothing does (i.e., it's empty space.) Empirically, it turns out there's no other mass in there, so atoms are considered to be mostly empty space.
|
Everything is mostly empty space because it is made of atoms. The nature of protons, neutrons and electrons is that they can't be pushed together more than a certain amount. The reason why is "quantum stuff", a bit beyond ELI5, but roughly because they can't be confined into a smaller space. When the atoms of your finger come close to something else, or even the other atoms in your finger, the force stopping them getting closer than the distances allowed by their quantum nature translates to what we call "solid".
|
What did they do with the mentally disabled in medieval times?
|
They were cared for at home, or at religious institutions, as specialized homes for the insane were only established at the end of the medieval period. [Dolhuizen](_URL_1_) or madhouses were build in the Netherlands from 1425 on.
|
Mental disability is a very, very, very broad spectrum. Do you want to narrow it down somewhat?
|
Why didn't the USSR land a man on the moon?
|
A big part of the problem was that they lacked the heavy lift capacity to get men to the moon. It's one thing to send probes that to the moon; it's another thing entirely to send a manned spacecraft to the moon. Sergei Korolev, the mastermind of the Soviet rocket program, had developed the N1 rocket to be used in a heavy-lift capacity, like the Saturn V. However, there was some infighting among the Soviet government, because the N1 held little military value, so they didn't want to pursue it. But Korolev had friends in high places, so to speak, and was able to gain enough support for the program. However, when Khrushchev was overthrown in 1964, the N1 lost a lot of its support in the higher echelons of Soviet government. Then when Korolev died in 1966, his successor didn't have the connections Korolev did to keep the project well-funded. Those things all contributed to the N1 failing. Of the four N1 launches, all four were catastrophic failures.
|
Money and politics pretty much, NASA's budget is nothing compared to what is used to be and back then US was completing with Russia to be the first to the moon
|
Why is paper easily torn apart when we put it in the water?
|
Paper is primarily composed of cellulose, which is a polymer. The long chains of cellulose aren't aligned in any particular direction, so they tend to overlap each other. Nearby chains can hold onto each other via inter-molecular hydrogen bonding. When you add water to the paper, the paper swells, soaking up the water. The water molecules soak into the cellulose and weaken or break the hydrogen bonds between the chains, pushing them further apart. Analogously, imagine that you have a dozen people standing in a circle, trying to reach in with both hands and hold onto a small water bottle. Now imagine them trying to do this when their arms have swollen to twice their normal size and the bottle has been coated in grease.
|
It is made up of a lot of strands with their own tension, when you rip paper you are breaking a lot of strands at once. Its like a rapid fire popping sound of that tension being released.
|
How would the destruction of the moon affect the Earth?
|
[What would happen if the moon were destroyed?](_URL_0_) This site presents a few scenarios. If the moon were broken into pieces, the debris would likely come into our atmosphere, block out the sun, and destroy all life. See the link above for alternatives, such as the moon somehow just "disappearing" or "vaporizing."
|
animals would go batshit without the moon to guide their natural rhythms. we would lose the tides, and more importantly the earth's rotation would be affected, we would start to wobble. right now the moon has a stabilizing influence on our rotation. The moon also acts somewhat like a shield for large meteors picking off alot of them before they hit us so our odds of a deep impact style strike go way up. if the moon were to break apart into pieces we'd be well and truly fucked when the first big chunk of it hit us.
|
Gold is often found as pure gold nuggets. What other elements can be mined in non-compound, pure elemental form?
|
Metals found in their pure state are referred to as Native Metals and the [wiki page](_URL_1_) lists the different elements which can be discovered in native form. In addition to gold, it appears that copper, silver and platinum are the other elements which have been commercially mined in native form. In the case of copper, the [upper penninsula of Michigan](_URL_0_) is particularly rich in copper but the last native copper mine ceased operation in 1969.
|
Rarity. Copper having an atomic number of 29, compared to iron of 26 and gold of 79, we can draw a single, simple conclusion: Copper and gold both do not form in stellar nucliosynthesis as this process ceases to fuse materials past iron, however copper is much closer (3 protons, compared to 53) and as a result would be produced in greater proportions in stellar collapse, the source of all elements beyond iron. For reference, if we took all the gold we have ever mined [based on Warren Buffet's numbers], it would form a cube 20m on all sides, weighing about 171,300 tonnes; in comparison, this is 15x more gold than we had mined by 1500 CE. For comparison, we began producing this much copper *every year* around 1900; today, we now produce approximately 100 times this amount every year.
|
Why do thai people write "555555" when they are happy?
|
Because the pronunciation of 5 is " ha " in thai its the equivolent to lol in english I assume that you saw this in online games Source : I'm Thai
|
Thai people risk getting arrested for eating a sandwich in public, for reading books like 1984 in public, for the three-finger hunger games salute, playing a video game with military dictatorship theme, wearing a t-shirt with any kind of "political" message even if it just says "Peace", holding a blank paper, for gatherings of more than 5, for posting online anything against the king or against the military coup. Police will pay anybody who rats out somebody that was talking against the coup. Thai people are ordered to be happy. The current general/prime minister stated that he will enforce happiness if required. Not surprisingly, the path to happiness is for people to obey him. Which shouldn't be hard considering that media declared him to be the Thai ideal of a man - from physical beauty to brains. To be fair to the military, they didn't just order happiness. They also organize parties in parks with free food and army dance numbers. The general also wrote a soap opera for people to be happy.
|
What would happen in the US if all of the homeless/impoverished people just disappeared?
|
A lot of those people have minimum wage jobs and just don't make enough to really get by. The base of the economy - unskilled laborers, low-level service - would be removed, and everything would collapse like a house of cards. On a side note, as a college kid, at least I wouldn't have to worry about finding a job this summer.
|
Before the welfare state this was how poor people survived when they had no assets and were out of work. The food was pretty poor and families were split up, however it was better than being out on the streets.
|
When your hands are cold and they warm up too fast, why does it hurt really bad?
|
It's due to reactive hyperemia. Basically when it is cold, your body cuts down circulation to your extremities (like fingers and hands). Cutting down circulation means that there is less blood exchange with tissues (so less oxygen and glucose delivered, and less waste like carbon dioxide, hydrogen ions, et cetera is taken away). These waste products are also chemicals called vasodilators which enlarge your blood vessels and allow more blood flow. But when your hands are cold the blood vessels aren't allowed to dilate, and these vasodilator chemicals keep accumulating since they aren't being washed away by the blood. When you come back inside, the warmth restores circulation to your hands, and since there was a buildup of vasodilators, your blood vessels enlarge TOO much. This excess blood flow and vasodilation triggers pain receptors. This link's up with Raynaud's syndrome because individuals with Raynaud's are very susceptible to cold-induced cutting off of blood flow. Hope this answers your question!
|
Very interesting subject. The reason lies in the cold-receptors of your skin, that measure cold. If you slowly increase the heat of the skin you observe this: They usually have a maximum activity when they reach 25 celsius degrees, stopping at about 30-35. A curious phenomenon, though, is that they start being activated again when the skin reaches about 40 celsius degrees. So even though your hand is scalding, your brain thinks it is quite cool. Fortunately for us, there are also heat sensors that have a maximum activety at 43 celsius. (Curiously enough, they stop at 45 degrees) This phenomenon is called an inappropriate stimulation of receptors. Another example is the stimulation of cold receptors in the mouth after eating a mint. Menthol stimulates this receptor.
|
How does Green screen work?
|
If you want to use a computer to put an image onto a video, you pretty much have to do it frame by frame. Modern software can speed this up a lot but sometimes you just want to change a background or something. So you pick a colour that you know will not be in your frame, make sure its evenly lit up. Then you have some software that will replace the green in the video with whatever you want. For this, a light green is usually chosen.
|
Monitors emit light, paint absorbs light. Example: White light from the Sun (consisting of all colors at once) hits red paint. The paint absorbs all the colors of light except red, which bounces off and hits your eyes. So, you see red light, and the paint looks red. Because of this, you can use red, green, and blue light and combine them to form any combination of light colors you want, but you use red, yellow, and blue paint to take all of the right colors out of white light so it looks like the color paint you want.
|
How are allergies developed and why aren't there any cures for it?
|
Have to jump in on the 'no cure' part - there actually is a cure! With some allergies, they can inject you with small amounts of the allergen for a long time, until your immune system gets used to it. The success rate varies but it's helped quite a lot of people I know.
|
Allergy is a very complex proces even for specialist, but if explain it in general allergy is a defect of immune system when immune cells thinks that some safe substances are dangerous (like some food, pollen or animal fur) Immune cells are located almost everywhere in organism, also there a lot of them in skin, so if even allergen came thorough stomach or nose it still affect all the organism and make cells produce inflammatory markers which couse high temperature, swollen, redness and itching. Since skin is visible to us we can see consequences of allergy there. Also there are some autoimmune diseases that aren't connected to special allergen, just immune system goes crazy and start local inflammation with no reason (dermatosis, eczema and others)
|
what happens to grass durning winter?
|
It hibernates (lies dormant). Plants need sun and water to live, both of which are scarce during winter. So the plants go dormant to conserve energy until snow/ice begin to melt and the days get longer.
|
Most plants that live in areas where it gets cold enough for snowy winters store energy in their roots in form of starch. This way when spring kicks in they have a reserve of energy to sprout new leaves to replace the ones that died from the frost.
|
How do babies scream for so long without 'losing their voice'?
|
Babies are born with natural, perfect resonating ability. Through parenting, imitation, and socialization, some of us move away from the natural instinct towards a "good" standard. Babies don't tire their voices because their voices are not working--they're just resonating. I'd wager you lose your voice after a gig because your technique is less than ideal. Watch how a baby laughs or cries. See the way their stomachs move in (in!) when inhaling before laughing or crying and out during the vocalization. Look at their mouth positions: all smiles in the "ah" shape. A baby does not manufacture a sound, it just sounds. Basically: babies have perfect vocal technique through instinct. I'd discuss this with your voice teacher or find one of you don't have one. Source: Masters in Voice
|
Some Native American groups would practice muffling the sound by covering the babies mouth with their hand or a blanket of some kind, sometimes almost to the point of suffocation. This trained the babies to generally refrain from crying. While this may seem harsh, a crying baby posed a serious threat to the group. A similar practice was used with camp dogs. If they didn't learn to be quiet, through physical punishment or reward, the dogs would have to be killed or let go so that they would no longer be a danger to the group.
|
How does a tree attract lightning?
|
At risk of over-simplifying, pretty much everything will conduct electricity. How easily a thing conducts electricity is down to how much it resists the flow of electrons; its "resistivity". Compared to a piece of copper, you might see a tree as being non-conductive. This is because the resistivity of the tree is higher than the copper, which is a better conductor. However compared to ambient-temperature air in a non-ionized state (normal air), a tree is a better conductor for extremely high voltage electricity. Electricity always takes the path of least resistance, hence the lightning hits the tree instead of going through the more resistive air around it.
|
Speculation: The selection pressure is insufficient. Lightning doesn't strike often enough compared to the available population of trees to outweigh the selection pressure caused by competition for sunlight.
|
To what degree were the Confederate monuments, place names and so on meant to honor them, to promote the Lost Cause myth, or meant to show black Americans who was still in charge?
|
While it about the Flag, not Monuments, you may find this old [AMA on the Confederate Battle Flag](_URL_0_) to be of interest\.
|
The Lost Cause Mythology After the war, a number of ex-Confederate officers made an extensive effort to essentially rewrite the history books to romanticize antebellum Southern society, build up the careers of their heroes (such as Lee and Jackson) and smear those of their opponents (such as Grant and Sherman), and muddy the waters so the Confederate cause was about "states' rights" and "resistance to Northern tyranny" rather than the preservation of a system of race-based chattel slavery. This interpretation caught on around the country during the late 19th and early 20th centuries. You can see just its cultural impact during that time in films like *Birth of a Nation* and *Gone With The Wind*. It acted as a means to reconcile Northern and Southern whites but in the process sacrificed the freedoms of African-Americans. [Relevant AskHistorians thread](_URL_0_)
|
How much did the average person really believe in the New England vampire scare?
|
...Tell us more about the New England vampire scare. Where and when?
|
I found an article (in Dutch, unfortunately) from De Telegraaf in 1898 where a Greek peasant, who supposedly died from typhus, rose from his open coffin during his funeral service, causing the mourners to run from the church, screaming "a vampire, a vampire!". The poor man was able to walk home and it took several hours before anyone dared to approach him. The Greek superstition that serious sinners will rise as vampires is mentioned, which is also mentioned in Lord Byron's poem [The Giaour](_URL_0_). A scan of Dutch newspapers show that the earliest references (1835 and later) refer either to the actual south American vampire bat or to the vampire literature of Lord Byron and his successors.
|
Why can't I see clearly under water?
|
When light moves from one material to another, when they are different densities it is deflected by a set amount. Now usually our eyes use the deflection that happens between air and the material inside our eyeballs to help focus the light onto the back of your eye. You have a lens inside your eye that can change the amount light is deflected in order to "finely tine" the focus, depending on how close or far the thing you're looking at is. However its tuned to expect the deflection from air to eye. When your eyeball is directly exposed to water, the amount light is deflected by is different (it becomes almost nothing actually) and the lens in your eye is not set up to focus light with that little amount of deflection, so you see things blurry.
|
Water clarity is usually characterized in terms of [turbidity](_URL_0_). To measure turbidity, you shine a light through the water and detect how much is received on the other end. Water with high turbidity means there are a lot of particles in the water that blocks/reflects light from passing through. The actual turbidity level can be influenced by a large number of factors, including temperature, pH, concentration of solutes (including nitrates), etc. - because these factors all contribute to the level of suspended solids in water. I won't go into too much detail here - but I'll give it a shot if you want more detail. tl:dr Lots of factors contribute to the amount of stuff in water that blocks light from passing through. edit: grammar
|
If an object falling into a black hole would never appear to reach the event horizon to an observer, then wouldn't a black hole be a preserved image of everything that it's absorbed?
|
It would be, except that as things slow to a distant observer as they near the horizon, they also get dimmer. An object at the horizon (to a distant observer) is infinitely redshifted. That makes the horizon, and everything on it, invisible to the outside universe. (It's also an interesting question that something falling into a hole will make the hole larger, at which point something that previously wasn't at the horizon now *is*. It also implies that we can never actually look at a black hole and conclude that something is outside its event horizon; merely that it's outside its *apparent* horizon. It's possible, if extraordinarily unlikely, that that horizon will grow in the future and things that are safely outside now, including ourselves, will be inside in the future. On a more practical level, this makes numerical relativity exciting if you're not careful with your coordinate grid.)
|
The apparent horizon is the radial distance from the singularity at which photons can orbit around the black hole. Within this horizon you could, theoretically, see multiple images of background objects because photons from these objects have circled the black hole once or more. The event horizon is the threshold at which the escape velocity from the black hole is the speed of light. Beyond this, nothing, not even light can escape(with the theoretical exception of Hawking Radiation).
|
how Stephen Hawking's talking machine works.
|
He does not often speak in real time. What he has to say takes time to generate. When you see him give a speech or greeting, it was all done before hand. He just rolls up and pushes a button then hangs out. It must be quite boring for him. He also hires special assistants to assist with his work so he can "say" a few things and they will be able to complete the theory or formula while he watches. There was a show where one of these assistants explained the process.
|
_URL_0_ He uses a sensor that he can control with a muscle in his cheek to type on a computer. The cursor scrolls across the screen over the letters and he stops it when it gets to the right one, plus there is predictive text. Then a text to speech program plays it aloud. I have a friend who uses a Dynavox for the same purpose by clicking a button on her wheelchair's headrest with her head. It can take a while to have a conversation.
|
How do dumb people get into such positions of power?
|
_URL_0_ People are promoted to their level of incompetence.
|
Just to clarify, the President has that power their entire term, they just usually wait till they're on their way out
|
Would Non-Newtonian fluids behave differently on a different planet, or in space? Do things like temperature, gravity and environment determine this Non-Newtonian state?
|
Non-Newtonian fluids do not behave as they do because they are near a phase transition. They are suspensions of microscopic particles (varying widely between different fluids) that interact with each other. Depending on the amount of force, the interactions between these particles suspended in the liquid can be more or less important to the properties of the liquid. Though /AskScience isn't a fan of Wikipedia articles, [this one](_URL_0_) does a particularly good job of describing the physics in more detail. That said, if you put the system in an extreme condition where the properties of the solvent molecules carrying the particles begin to change, you could still see a deviation from "normal" properties that are observed far from a phase transition.
|
Depends how you define 'more fluid'. It seems like what you're thinking is 'less viscous'. In which case, yes, absolutely. The 'sludgy' fluids you're thinking of are non-Newtonian, like corn-starch and water, which gets thicker (more viscous) when you apply a force to it. There are also shear-thinning non-Newtonian fluids which get thinner (less viscous) as you apply a force to it. It doesn't really make sense to compare these different classes of fluids to water, at least in the context of this discussion. However, there are Newtonian fluids (fluids with a constant viscosity) that have a lower viscosity than water at room temperature. For example: Acetone and Diethyl Ether. We could be pedantic here and include gasses in our list since they are technically fluids, and they have very small viscosities, however they are not liquid of course. On the extreme scale there is Superfluid Helium, which is a fluid that looks like a typical liquid but has zero viscosity. Very cool stuff!
|
Can constant use of UV-Blocking contact lenses(or perhaps sunglasses) affect mood?
|
Light therapy lamps for SAD typically do not contain UV light, just a lot of visible light. Additinally, UV light interacts with your skin to create vitamin D, not your eyes. I would guess that the lethargy is just from lack of light in the winter in general rather from your contacts.
|
Yes, UV light is harmful for your eyes and can cause [welder's flash](_URL_0_).
|
When you feel like your heart is skipping a beat, is it really skipping a beat?
|
I've been tested for this, and in my case it is that one heartbeat happens sooner than it normally would, and then the next heartbeat happens when it normally would in regard to the first of the three heartbeats, leaving more space between the second and third heartbeats, giving me that fluttery feeling in my chest.
|
We cannot directly control our heart beat because the heart only has autonomic nerves. These are involuntary. Breathing, blinking, swallowing all have muscles that have somatic nerves, meaning we can voluntarily move them. They are also autonomic responses, however we can control certain muscles that allow us to resist this.
|
why do smoke detectors run on batteries? Wouldn't it be more convenient to wire it in like a light?
|
The majority of smoke detectors I've owned were wired in to the houses electrical supply, and just use batteries as backup.
|
Because fire may cut off power before the smoke reaches the alarm. Especially since quite a few fires start as a result of electrical issues. Making it completely self contained also means it's easier to install. And that's only home smoke detectors. Smoke detectors in large commercial and industrial buildings generally do run off main power (often connected to backup power) as they feed their alarm to a central source which can keep track of each detector and see when it's offline and can activate the whole system if something happens.
|
When someone dies with their eyes open can they pull their eyelids down and they will stay shut after Rigor Mortis?
|
So I'm an EMT who's been involved in several coroner's calls to take stiffs to the morgue. It really just depends on how the individual died. Traumatic injuries such as a bullet wound to the head in a sheriff's office, eyes open. Aspirating on mucus in your sleep, eyes closed. I've transported a few heroin overdoses and they have mixed results. However, rigor mortis takes some time to kick in, it's not just set from time of cardiac arrest. So if a person has died very recently ( < 90 minutes) the eyelids would still operate smoothly from outside manipulation. But after a couple of hours, it would probably still be possible, would probably take more effort than just passing a hand over their eyes.
|
Upon death, many peoples eyes are prone to opening. Obviously, it'd be pretty scary to see a dead person's eyes opening during a viewing so in the past, sewing the deceased person's eyes shut was the best way to prevent that from happening.
|
How remote controls work
|
Most remote controls are *infrared* remote controls. These use a kind of invisible light called infrared. They have an LED on the front (similar to indicator lights on electronics) that emits the invisible infrared light in pulses. Different patterns of pulses correspond to different functions. The device you're controlling has a sensor on the front that detects infrared light, attached to a controller which decodes the pulses, and if the pulse is in a pattern that corresponds to a particular function of the device, it performs that function.
|
The remote has an infrared led light that pulses depending on what button you press. Example: Volume Up 2 quick pulses and volume down 1 long and one short pulse. Then that's picked up by an infrared receiver in your TV or whatever. That receiver only picks up infrared light. Using that the piece of equipment you are controlling reads the pulses and know what button you press. Edit: if you meant why it works using brute force than it's because when you hot it just puts a loose contact back in place, thus making a good connection with the battery.
|
what happens exactly when you blow out a candle or shake a match in order to extinguish the flame?
|
The candle is surrounded by a pocket of flame that keeps it warm. Since it doesn't have very much mass, it doesn't take very much cold air to cool it down until it's too cold to burn. Shaking the match pushes this hot air away and replaces it with cold air. It's the same thing that happens when you blow on it.
|
This question has been asked numerous times in the past. Use the search! The last time I saw this question asked I responded: > You are removing the fuel. A candle flame consists of a pocket of vaporized fuel (wax) whose surface burns, fed by oxygen. When you blow out a candle you are blowing away that pocket of vaporized fuel before it has a chance to be replenished. You have blown out the candle. The candle remains hot enough for a while to continue issuing fuel vapor, but you have blown away the burning surface that previously provided enough heat to ignite the vapor. A match is similar -- it's not just that you are reducing the temperature (as others have asserted) but that you are removing the vaporized fuel. The match will continue to be hot and will emit some ignitable vapor for a short time after it has been blown out, but since the flame is gone the source of high-temperature ignition is gone, and it can no longer self-ignite.
|
Why, as a fertile female, do I find human babies repulsive -- yet fawn over/have a strong instinct to nurture baby dogs and other animals?
|
Human beings are complex emotional creatures. I don't know exactly what it could be, but maybe your mind assosicates babies with responsibility and headaches, you may have seen others grounded by responsibilities and work when they have babies. So your mind associates them with that. But animals are far less than that, and are many times just cute things you can cuddle and play with. So your mind associates them to good things. Also, babies grow up to become actual people, while puppies will still just become dogs, and dogs will always be under your command and loyal to you, wile babies will ofc grow up. Just my opinion.
|
Part of the reason we like petting and caring for animals, even if it’s just for a minute or two, is because it causes our brains to release a chemical called Oxytocin, which is a “feel-good” chemical that’s responsible for our more nurturing aspect of our humanity. you know how no one hates a baby (as long as it’s not crying), and how everyone wants to smile and touch the baby’s cheeks? It’s the oxytocin in our brains that gets released, it’s kinda for survival, so humanity protects our young and therefore our ‘pack’ whether we’re caring for a little dog, or a little child. Dogs have oxytocin as well, mothers especially after they give birth, that’s why dogs are so protective of their young.
|
Why am I starting to go bald on the top of my head while growing a healthy mane on my balls?
|
If you're 5, and going bald with ball hair, DOCTOR, NOW.
|
It does do that. This is most commonly observed with body hair, but head hair will do the same thing when sufficiently long
|
What happens when you don't pay hospital bills?
|
If you don't pay your hospital bill (or any bill for that matter) it's considered a debt you owe. The person who holds that debt can sue you in court to collect that money. The court can force you to sell things you own or directly take money out of your paycheck in order to pay back that debt.
|
Hospitals have to provide life saving treatment to anyone, no matter their economic situation or their insurance. And even if you can not pay for yourself you will get a bill and it will get sent to a collections agency when you do not pay. The issue is that hospitals do not get paid for their expenses in those situations. So the doctors and nurses knows that if they spend too much money treating patients who can not pay for themselves then they might not get as much raises or the hospital may even be forced to downsize. So a lot of people without insurance gets worse treatment then those with insurance even though this is illegal. And yes, people without insurance does die more often from appendicitis or infections then those with insurance. Another issue is that going to the hospital might mean you go bankrupt so they do not go to the hospital as often. This also reduced their life expectancy. So yes, it is a shitty situation.
|
As a segment of the population, did European nobility in the Medieval, Early Modern and Modern eras die disproportionately in war?
|
Yes, at least in many instances. I know that David Cannadine has demonstrated that WWI took a disproportionate human toll on the British aristocracy. I know his purpose in relating that is to make the point that even as late as 1914 the aristocracy were still committed to a warrior class ideal and that this ideal's existence had usually meant the aristocracy died disproportionately in war. At this very moment while I slack off at work I can't provide precise citation of statistical proof of this for earlier wars, but maybe I'll be able to add something on that later.
|
Hi! Not to stifle further conversation, but you may find a similar question I answered a while back on [the fate of the Gallo-Roman aristocracy in France](_URL_0_) to be helpful. I'm happy to revisit it with any follow-up questions you may have.
|
What makes Tornado Alley so prone to Tornadoes?
|
It has to do with geography. Because of where the area is located, warm air masses and cold air masses often come in contact with one another. Those are the main ingredients for a tornado.
|
It's due to the size of cities. They can go through download areas, but you have to realize that downtown areas are very very small in comparison to the size of tornado alley. [List of downtown tornadoes](_URL_0_)
|
Assuming we start pressure cooking algae to make biofuel, how probable is it that we will cook off our oxygen supply over time?
|
Oxygen isn't a finite resource, it's constantly being cycled as part of our biosphere. The probability is either one hundred percent, in that we destroy everything which can 'create' oxygen or zero percent, in that we do not. You're asking us to predict the future with an unknown set of variables, something we can't do without speculating.
|
Oh yes - ultimately, it's the same basic reactions, so that burning biofuels isn't cleaner than burning fossil fuels. HOWEVER - the carbon in those biofuels was recently taken out of the air by the plants or algae used to create them - for fossil fuels, that happened millions of years ago. So it's more of a break-even in that sense.
|
The difference between roads, avenues, streets, lanes, ways, etc
|
They are in fact different, mostly in layout. A road is one that runs between two points. A street is within a town, lined with homes, shops, and such. A drive or driveway leads up to a private house. An avenue is usually lined with trees and homes and shops on either side. A way is a smaller street off a road. A court is a short street that leads up to a complex or compound. A boulevard is mainly a scenic avenue, lined with trees, flowers, bushes and greenery. *Edit: A crescent is self-explanatory.*
|
In the U.S., there is no standard terminology. A given road may be called any of these at the whim of the municipality. There are a few general tendencies, however: - A turnpike is a toll highway. - A boulevard is usually a major road. - A court is most often a short road with one outlet (a cul-de-sac). - In a planned city, the "type" of road may denote orientation (e.g. Manhattan, where streets run east-west and avenues run north-south.
|
how is it earthquakes have a single location?
|
So I made a [crude image to depict the epicenter](_URL_0_). Essentially you have two plates slipping by each other, but then they hit an irregularity, the larger the irregularity the more force it takes for the two plates to slide past each other. There are many irregularities, so you get many earthquakes, but most are small, the epicenter happens at the irregularity, the larger the irregularity the larger the earthquake.
|
Earthquakes have collapsed steel structures, notably in 1985 in Mexico City. Damage also occurred to the connections in many steel buildings during the 1994 Northridge Earthquake (but there were no collapses). Lessons from these and other quakes have been incorporated into modern codes - especially in California, which has the most advanced seismic building code in the world.
|
when one string suspending a mass and the other string is suspending from the mass. Which one breaks when you pull on the lower string?
|
As far as I can tell this is what is happening: When he pulls slowly, the top string has more force acting on it because it has to support the weight of the block as well. As he pulls harder the top string will break first because it reaches the failure point first. This is what you intuitively expect. However, when he pulls down fast and hard, the bottom string is already experiencing it's failure load and breaks before being able to effectively propagate the force.
|
as /u/BooooooooooM stated the vibration is at a lower frequency which means that the string is actually oscillating fewer times per second, meaning the same energy input will create a longer sustain. Also the lower strings are much more massive than the higher strings, meaning that they will resonate for a longer period of time.
|
If you lit a match in a zero-G environment with no air movement, what would the flame look like?
|
If you want to see a [video of one in action, there is one here](_URL_0_). It shows a flame in microgravity which is about as close as we can get to Zero G without going into space. It was filmed at NASA's Glenn Microgravity Drop Facility, and shows the spherical diffusion of the 'flame'. Obviously normal flames have a familiar shape to them as the hot air rises. The 'hot air rises' phrases, while true is probably not the best way of thinking about what is happening. It is probably simpler/easier to think of heavy things falling; so cold/normal air has a greater density than warmer air and consequently displaces the warmer air. As a consequence of the cooler air displacing the warmer air, the warmer air rises. But obviously warm air doesn't have some magical antigravity property, and warm air is still attracted to earth. **Tl;dr: In zero g/microgravity there is no such difference and consequently the [burn is spherical](_URL_0_).**
|
_URL_0_ It expands radially in all directions, then have problems with oxygen feed. In gravitational fire, you feed in oxygen at the bottom of the flame, with no gravity, the ignition consumes all the local oxygen and then you have problems with fuel o2 ratios.
|
Why does it feel like time slows down when you drop something, or if an accident happens?
|
Looking [here](_URL_0_)... it seems like your perception of time doesn't change, but the amount of memories you have of it increases. What we *think* is happening is that the amygdala (a more primitive part of the brain), during emergencies, opens up a set of extra "memory space" that aren't a part of everyday ho-hum memory making, presumably to increase your attention during tense situations. The end result is that reflecting back on the event, you have a richer recollection of what happened, and thus the perception that the event "took longer". The same sort of thing happens as you age. When you're a child, more events in your life are novel and noteworthy, and you retain more memory of those events. As you age and more and more of your everyday events are just the same old stuff, less of your days are "worth" remembering, and the years seem to "go by faster and faster".
|
As a child, you are frequently exposed to new situations and stimuli, and as a result must constantly determine what an appropriate response to these situations would be. As a result, you are forced to live quite literally 'in the moment'. The amount of sensory information that your brain is processing results in the illusion of time moving slower. As you grow older, you encounter new experiences less and less frequently, and can therefore spend much of your life reacting through learnt routines or behaviours. This allows you to stop engaging quite so intensively with your current situation; resulting both in an improved ability to plan future actions, as well as the illusion of time passing faster. EDIT: Wording
|
Why do (a lot of) cars get optimal fuel efficiency at 55-60 mph/88-95 kph??
|
Because that's when they are most efficient. It's more about the RPM count, at those speeds most cars are around 1750-2500RPM, which is usually where they get the best MPG. By going say 80MPH, while you are traveling 1/3 faster than 60MPH, the MPG degrades by more than 1/3, due to air resistance and the fact that you are out of the prime RPM range. Think of it this way, if you had to travel 1 mile on foot, sprinting as fast as you can will get you faster than jogging, but by sprinting you will be dead tired aftward, while by jogging you will still have more energy left.
|
There are many good answers here centering on efficiency, and they slightly miss the point. Efficiency is NOT the goal in and of itself; rather efficiency keeps the total project cost down. Remember, this project is being paid for with YOUR tax dollars, and the contract was awarded to the lowest bidder. The lowest bidder, in turn, made that low bid by only budgeting ONE crew to put out and pick up road cones ONCE. Sorry, but driver inconvenience is rarely a priority. Minimizing cost is far higher. Efficiency is a factor only as far as it contributes to minimizing costs.
|
Why do Western news agencies conduct opinion polls in dictatorship countries, where having certain opinions is criminalized?
|
It garners public interest in western nations, which has the potential to raise the pressure on a government to act in a way that ends the dictatorships, or at the very least makes them put pressure on the dictators to be less dictator-y. Often these opinion polls are anonymous to protect the people participating in them to keep them as safe as possible, though most who participate do so accepting the risks.
|
Because humans run the news, and it's impossible to have unbiased humans. No matter what you do, someone will always leave something out that they think is unimportant but means the world to someone else, or say something in a way which unintentionally misleads. Also because all of our media is owned by massive multinationals which tell us things which help their bottom lines.
|
How can I write multiple files to the same hardrive?
|
Strictly speaking, they're not transferring at the same time. It's just that modern drives and controllers are so fast that it appears it's all happening at once. In reality, the data is being written out one piece at a time, sequentially.
|
Yes and no, you can't just solder usb drives together and make a bigger one, you will need a hub so the operating system can load the different hardware per each flash drive. And then from there you can format the cluster of drives with raid and make it appear as one solid chunk of memory. Oh and if your curious Raid 5 is for data redudancy and Raid 0 is for speed. Also [this picture](_URL_0_) of a bootleg hard drive was what my mind immediately went to.
|
Why does water expand as it freezes? Shouldn't it contract?
|
Water crystallizes as it freezes. The molecules in a crystal pattern take up more space than those in the random arrangement of a liquid, so the water gets slightly larger.
|
3 main reasons: 1. The earth is warm and the air is cold, so it gets heated by the ground 2. Water holds a lot of heat, it takes a lot of energy to change the temperature of water, and it is dependent on mass, so the thinner edges freeze first. 3. Higher pressure makes water harder to freeze (cause ice expands). So the deeper the body of water the less likely it is to freeze.
|
How much of a snake is tail?
|
The standard for body measurement in reptiles and amphibians is based on the location of the vent - the externally visible part of the cloaca (combined opening for waste excretion). In legged species, the vent is located near the hindlimbs. The length from vent to tail is considered tail, while the snout-to-vent length is representitive of body size. [This paper](_URL_0_) describes differences observed in tail length of male and female snakes. Some snakes do develop hindlimb buds (the first part of limb growth) as embryos, but don't continue development. [This paper](_URL_1_) has a lot of good info if you are interested, particularly about the region in which "torso" *hox* genes are expressed, which essentially results in exclusion of hindlimb signals in snakes.
|
Depends on the snake. Many of them build up immunity in order to protect themselves in the case of an accidental bite.
|
From my 7 year old daughter: Why does it look like steam comes up when I add cold water to ice cubes in my water bottle?
|
Steam refers to gaseous water, and is invisible. What you refer to is water condensing in the air - gaseous water forming droplets when it turns from gas to liquid. This occurs when the water vapour cools down enough to return to liquid form. You commonly encounter this in two scenarios: 1. When you're boiling water, water vapour escapes from the pot. However, when it hits the air and loses energy, it condenses back into visible "steam". 2. When you have a very cold surface. The cold surface cools down the air immediately around it, and if you cool it down below its [dew point](_URL_1_), the air cannot hold the water vapour and they condense. You will observe this on top of ice cubes alone. Adding water to the ice cubes just pushes this air/condensation mixture up the bottle. More extreme examples would be the condensation you see from [liquid nitrogen](_URL_2_) and [dry ice](_URL_0_).
|
Steam is an invisible gas. What you're seeing is the steam cooling off & condensing into visible water droplets because there's less heat in it.
|
Why don’t viruses in virtual machines effect the host computer?
|
A virtual machine is completely isolated from the host computer. In some cases virus can actually affect a host computers, but it doesn't happen often.
|
In the early days of hacking, viruses were created on test computers. A machine that has all the basic components of a computer, but doesn't have anything but an OS installed. It's just a dummy. Later, we created virtual machines for that. Basically, a whole computer that is separated from the rest of your computer by an invisible wall. This is how most viruses are created nowadays. However, certain particularly nasty viruses can get through even virtual machines. We're back to using dummy computers that aren't connected to anything else.
|
Why can skiers travel faster downhill than human terminal velocity?
|
Terminal velocity is based on air resistance. The quoted value of human terminal velocity is likely based on a normally clothed individual falling face first with their body square to the direction of travel. If they turned so were falling either head first or feet first, they'd probably fall quicker. Likewise the clothes they're wearing makes a huge difference; the looser they are, the greater the drag The skier was likely wearing aerodynamic clothing with an aerodynamic helmet and in an aerodynamic posture, all to reduce drag and allow them to "fall" (ski) faster
|
If you watch at the beginning of a run, you'll see that the skier always skates a bit out of the gate. A few really aggressive pushes against the snow to get up to speed. That speed will be faster if the racer is stronger, which is typically true of men as compared to women. A huge amount of time can be cut off a run simply by having a quick start. Furthermore when you are going 30-40 mph around a turn it takes a lot of strength to push back against the centripetal force, so a racer can maintain a higher speed if they are stronger. Being heavier helps men maintain higher speeds as well. When you watch the racers make turns you will see that in order to take the tightest line around a turn, a racer will often run into the gates. If the racer is heavier they will have more momentum and therefore hitting these gates will slow them down less.
|
How .99 repeating equals 1
|
A little backwards approach... 1/3 * 3 = 1 1/3 is decimal isn't perfectly writable.... .3333 < 1/3. .3333333333 is still < 1.3. .333333333333333333 is closer, but still isn't 1/3. The more 3's you put in the decimal, the closer it gets to the actual value of 1/3. To get ALL the way there, you'd need to put an infinite number of 3's there (that's the hard part to grasp). Now, take that .33333... that goes on forever, and multiply it by 3, to get .99999999999... since .33333... is 1/3, then .99999.... has to be 3/3, or 1. The repeating (infinite) version of the decimal is how you tend to be confused by this. Think on that, once you understand the idea, it does make sense.
|
its very simply read in 'columns'. each column is worth a value. you add the values together anywhere there is a '1'. example; 10010 is actually like 16 | 8 | 4 | 2 | 1 so there is a '1' in column 16, and a '1' in column 2. what is 16+2 = 18. that's literally all it is.
|
How come Japan was able to rapidly industrialize and rise as an imperialist with a lack of natural resources?
|
the value of natural resources as a source of national power is VASTLY overrated. what is most valuable in the world is human, social, and institutional capital, and meiji japan had organizational and social capital in spades, which allowed them to do the things they needed to to acquire other sorts of valuables.
|
Relevant: [How did Japan manage to get the edge on the technology industry?] (_URL_0_)
|
^ USA civilians killed during WWII on mainlnd
|
Only six American civilians were killed on the US mainland during WW2. They were Elsie Mitchell (who was pregnant at the time) and her Sunday school class of five children. They were killed by a Japanese fire balloon that landed near Gearheart Mountain in Oregon. The remnants of the balloon were discovered by the group while they were searching for a picnic location. The payload did not detonate upon landing, and investigators theorized that it was triggered when one of the victims kicked it. Source: *"Daddy's Gone to War": The Second World War in the Lives of America's Children* by William Tuttle.
|
Probably the US Navy during WWII had the highest K/D ratio in history if deliberate killings of civilians aren't counted. If they are, then probably the Imperial Japanese Army in China. It cannot be overstated how effective the USN was in WWII. After 1942, the USN could be best described as a colossal grinder into which the Japanese fed men, ships, and planes.
|
Can radio stations track the number of people listening, and if so, how?
|
There is no way for stations to know who is listening because the communication is completely one way. _URL_0_
|
They don't. They do a poll. They look at a map and say "there are 3.5 million people in the area where they can easily listen to this radio station, let's call 3,500 of them and ask them if they've listened to the station in the last week." So they do it, and they find out that 173 of the 3,500 people have listened to the radio station in the last week. So they figure that 173/3,500 = 0.0494 is the fraction of people in the area that listened to the radio station in the last week. Then they multiply by the total number of people in the area: 0.0494 * 3,500,000 ~ approximately 173,000 listening in the last week. With something like cable TV, you can get direct data, because the cable box can report back to the cable company what channel is being watched, but with broadcast radio/TV, there isn't any effective way to tell.
|
If two objects were brought to absolute zero, would they pass through one another?
|
Electrons would still move at absolute zero, that's a common misconception.
|
No. Ignoring fancy things like the Cosmic Background Radiation, everything with a temperature above absolute zero is constantly emitting black-body radiation ("thermal light"). As nothing in the universe is truly absolute zero, then there is no box you could make or place you could find where you won't be hit by this emission from something.
|
What are Ghz and what do they mean when it comes to computer specs?
|
Hz is a measure of frequency- the number of times something happens per second. If something has a frequency of 3GHz, it means that it happens three billion times per second. In the case of computers, that's the speed of its internal clock. A single operation in a computer can take multiple steps, and the clock speed tells you how long it gives each step to complete. A simple operation, like addition, might only take 1 clock tick to complete, while a more complex operation like trig functions, can take over 100. Clock speed by itself doesn't mean much. You can use it to directly compare processors of the same series (so you can compare a 4th gen Core i5 with another 4th gen Core i5 processor), but different series of processors take different amounts of time to complete each operation, and a 3GHz processor that can finish a task in 100 clock cycles is faster than a 4GHz processor that takes 200 cycles to do the same work.
|
number of cores and clock speed (GHz) do not necessarily indicate raw processor power. You also cannot add the GHz of multiple cores to get a number that means anything.
|
In a zero-gravity environment, does acceleration of a spacecraft opposite the inertial vector generate "artificial gravity" for the passengers? E.g. decelerating from high speed upon reaching the halfway point of an interstellar journey.
|
Yes. In fact, acceleration in any direction will appear identical to the passengers (if they don't look out of the spacecraft). It doesn't have to be in a specific direction.
|
No, there is no such thing as artificial gravity outside of sci-fi. The only thing we have in theory is having a vessel rotate around its own axis and use the centrifugal/centripetal force as a substitution for gravity, but even that we only have in theory. This sort of artificial gravity works best for larger structures, larger than we have built any so far. Also one of the reasons we send people into space in the first place is to have them study zero-g (actually microgravity) creating artificial gravity would sort of defeat the purpose of going there in the first place. If we ever send people to Mars or father away we might make use of that technology, but we haven't really so far.
|
Is "potential energy" actually energy? Or just a descriptor?
|
> Is "potential energy" actually energy? Potential energy is only defined relative to a point of reference. There is no such thing as "absolute potential energy", which is what you intuitively seem to identify as being "not real". There is a difference in potential energy between a boulder on a hill and a boulder in the valley below. This **difference in potential energy is absolute**. When we say something like a book on a table has potential energy, we implicitly define the ground as a point of reference, relative to which the difference in potential energy is measured. > Or just a description? Of course it's just a description. Like every other form of energy as well. "*Energy*" is nothing tangible. It is simply a number that seems to be (mostly) constant in our universe, if we add up all the forms of energy we know.
|
I think you've just gone around and went right back to the very definition of energy - it is a mathematical construct that quantifies the _potential to do work_, so despite the name "kinetic energy" not having the word in it, you've recognized that the concept is still there in its original definition.
|
How do engines react so quickly to changes in air/fuel intake?
|
Sensors feeding information to a computer that electronically controls the fuel injectors. Your foot on the gas pedal opens a valve that lets air into the engine. There are sensors before, at, and after that valve talking to the computer. Then there are more sensors telling that computer when to ignite the spark plugs to combust the fuel/air intake valves/injectors let into each cylinder. As long as all those sensors are telling the computer what it needs to know, the whole process goes pretty smooth at 700RPM, 5000RPM, or whatever speed you rev the engine.
|
There is a chain/belt/driveshaft coming off the engine that turns an air compressor that pumps high pressure air into the engine's intake manifold.
|
How long does the actually explosion of a super nova last? Is it seconds like a explosion on earth, or longer due to the sheer scale?
|
The supernova explosion itself lasts of order [100 seconds](_URL_0_). However, the effects thereafter can be seen for months or years.
|
A type I supernova begins when the star undergoes electron degeneracy collapse - meaning that all the electrons and protons in the star undergo reverse decay and merge into neutrons. The process takes about 20 seconds, which is a pretty amazing speed for anything to happen on the scale of a red giant. But other posters are right, the actual explosion (which happens when the outer layers of the star rebound against the newly-formed neutron core) would take several minutes to become apparent. Though still, that's incredibly fast for an enormous, billions-year-old star. edit: gilded! Thanks guys! (Not really, but I just always wanted to say that.) edit: gilded *for real!* Thanks! It's like my very own supernova.
|
Why do all kinds of vertebrates have tails?
|
Evolution doesn't select for useful traits, but rather select against traits that reduces the chances of an organism to pass down their genetic material. So in the case of the pig it is possible that having a tail did not give them a disadvantage in term of survivability and thus chances to pass down their genetic material, whereas for humans having a tail might have some detrimental effect on survivabilty. Hopefully this is somewhat helpful, I am sure someone else can answer your question better.
|
All vertebrates are craniates, and all craniates are chordates. Chordates have 5 things you need to look for. - Notochord: Pretty much the spine before it developed into a spine (which happened when vertebrates evolved) made of cartilage - Dorsal neural tube: Equivalent of spinal cord - Pharyngeal slits: Known as gill in fish, used in filter feeding in earlier organisms, we lose them during growth but they are visible early on in development - Post anal tail: Exactly what it sounds like - Endostyle: Traps food that passes through the pharyngeal slits by producing mucus in the early organisms, it's the thyroid gland in us Craniates are chordates that have a skull. Vertebrates are craniates that have a *bony* backbone, not just the cartilaginous one that is present in chordates.
|
Why when upside-down does blood all go to our head, but when standing up blood flow is normal?
|
The normal state of our bodies involves having to pump blood "towards our head" against gravity to reach our brains. This is different from the idea that we pump blood "up". When you are turned upside down, your body is still doing the work of pumping the blood "towards your head" but now it is also having gravity pull the blood towards your head too instead of away from it.
|
Because your circulatory system and heart is plumbed (fluid dynamics and whatnot) with the expectation that generally you remain upright. Gravity, blood vessel constriction, etc are all involved. When you are upside down, your belly organs press on your heart and lungs, which is pressure they are not accustomed to handle. Also, it puts more pressure on your brain, which needs a certain blood pressure. When you are upside down, higher blood pressure impacts its function including your balance.
|
Can holding a magnet to my vein cause a blood clot?
|
Magnetic fields on the order of 1-7 Telsa can have a minor effect on red blood cells, affecting the rate of relaxation of certain chemical functions [Source1](_URL_0_) [Source2](_URL_0_). These field strengths are not sufficient to stop the motion of red blood cells due to the very low amount of iron in the cell. There is only one iron atom out of every 16000 atoms in a hemoglobin cell.
|
Yes, [mu metal](_URL_0_) for example. You want a metal with high magnetic permeability to direct magnetic field lines away from a certain area.
|
What is the purpose in geting stem cells injected into you.
|
The idea is that stem cells can turn into any cell. Because that's what they do more or less. A fetus is made of stem cells. Like a blob of a couple dozen cells fetus (probably has a different name technically but I don't know or care). Some have to grow into heart cells, lung cells, skin cells, nerves, etc. So basically the idea is that you can grow or repair damaged things that you can't otherwise grow or repair.
|
One source of stem cells is aborted fetuses. The anti-abortion people got the idea in their head that *all* stem cells are from fetuses and it stuck.
|
Why have 10 ELI5 links shown up on my front page just now despite the fact I'm subscribed to 50 other subreddits including all the major default subreddits?
|
I'm not entirely sure, but from what I remember reading a while back, it has to do with the way that Reddit's ranking algorithm sorts the frontpage. It's the reason why you aren't subscribed to every single subreddit by default; all of the smaller subreddits would dominate the front page. I guess the ranking algorithm has something to do with the ratio of upvotes to the number of subscribers to that subreddit.
|
When you look at the front page, you know right away what subreddit you are looking at. There might be many diffrent subreddits sharing your front page, and the ELI5 lets you know that That post is from this subreddit.
|
why do people pay large sums of money to kill animals for fun?
|
Probably the same reason people pay large sums of money for drugs, concerts, trips, anything else. It's a unique rush. I'm against it personally but I assume the novelty of it is the appeal.
|
We're an inherently violent species. Historically humans hunted animals for their food, and fought other humans for access to resources (like food, space, mates, water supplies, shelter).
|
How could zero gravity affect whisky maturation?
|
Sorry to go off topic, but I read that as whiskey masturbation (in zero-g!) and had moment wondering if that was a thing...
|
It would boil, whether there is gravity or not, in a vacuum. You could get a spherical shape if you had it in a pressurized environment e.g. on the ISS. This is also not "without gravity" but often what people think of when they say a zero grav environment, since it is in free fall (you and the water could float).
|
How were we able to measure how big the sun is?
|
Combination of two methods for direct observation: 1. Parallax: gives you the distance to an object. Works by making angular measurements of the distant object from two positions whose location is precisely known, and then using trigonometry to determine the distance. If you know two angles and a the length of one side of a triangle, you can figure out all the remaining dimensions. 2. Apparent width: Using the appropriate filter (welding goggles work well) one can measure how wide an object appears at a certain distance from ones eye. Once you know the distance to the object, you can determine how wide it really is by taking the ratio of distance and widths. (real width) = (measured width) x (distance to object - distance to measured width location) / (distance to measured width location). Of course in reality, the sun does not have a defined surface or edge, but this method will get you some idea of the scale of it.
|
The ancient Greeks did this without so much as a telescope. 1 - Erathosthenes calculated the radius of Earth by measuring a shadow at solar noon and the distance between where solar noon casts no shadow and this shadow. 2 - The size of the moon was then calculated based on the size of Earth's shadow on the moon during a lunar eclipse. You can then calculate the circumference of the moon's orbit and the moon-earth distance. 3 - Aristarchus then calculated the Earth-Sun distance, by recognizing that during a half-moon, the moon and sun make a 90 degree angle with respect to each other, you can measure the angle between the moon and sun, and with the earth-moon distance you can calculate the earth-sun distance. It's worth pointing out that with small angles, there is a huge source of error. Aristarchus was off by a factor of 20 or so, but it was still extremely impressive given the technology available at the time.
|
how does soy products (tofu, soy milk, etc) mimic estrogen and why is this a bad thing for us?
|
They contain isoflavones which have a similar chemical structure to estrogen. While studies have been conducted on the negative impacts the results are not conclusive though it's likely not to have adverse affects unless you regularly eat a great deal.
|
If I'm not mistaken, the reason is because soy milk doesn't contain casein. Casein is a protein found in milk from mammals, and has certain properties that make it a good at being a "glue" when this type of milk is added to recipes to make other things.
|
How is America not totally collapsing because of debt and the dollar bill losing value?
|
The US is in *such* a better financial position than it was just 7-8 years ago. No one's talking about the banks and financial system collapsing this time. Almost all countries have debt. Debt isn't a problem unless other countries stop believing you can pay it back eventually. The dollar is neither particularly strong nor particularly weak right now, compared to long-term historical values.
|
The United States Public Debt is about 72% of GDP. For reference, the U.K. is 91%, France is 94%, Germany is 80%, Canada is 86%, Italy is at 133% and Japan is at a whopping 226%. So when compared to the size of the economy, our debt is lower than most other high income countries. Public debt is expected to reach about 100% of GDP in 2040. The United States can spend money because people are willing to let us borrow money. People aren't particularly worried about purchasing treasury securities. The United States is considered the safest place to store your money and the dollar is the dominant reserve currency.
|
What the big deal is about the Hateful 8 being filmed in "70mm."
|
Regular 35mm is around 4K equivalent. 70mm is at most 2x wider and 1.2x taller, the Hateful Eight is 2.76:1, putting it at around 8200x3000. 70mm IMAX (Interstellar, The Dark Knight, Star Wars Ep VII (though only 1 scene), etc.) is 3x the size of 70mm (and rotated 90°), putting it at around 11800x8200.
|
"70mm" means that the film on which the image was collected and later projected is itself is 70mm wide. Think of older cameras that used 35mm film as a standard, but up this to 70mm and apply it to cinema. The reason 70mm film gets people excited is that the film allows for greater image resolution. Larger format films spread the image over a wider area, which allows for more detail to be collected by the pigments (or silver, for black and white) in the film. This gives a better final image. This is why lots of portrait studios used to use large format cameras since they generally give better images for the same film stock, and smaller size and subsequent "movability" was not necessary. If memory serves, 70mm can give films a really wide aspect ratio without loss of image quality. This allows you to do really epic film-making in a style along the lines of Lawrence of Arabia, Ben-Hur and the like.
|
if rat fleas are natural carriers of the plague, how come they don't transmit it anymore?
|
They do; there are between 1000 and 3000 cases of the plague reported annually. Rats just aren't as much of an urban epidemic as they used to be and the plague can be cured now.
|
Bacteria and viruses don't necessarily want their host sick, or even dead. Complications happen when the virus is in an organism it's not supposed to be in, and that organism isn't equipped to handle the virus. Rats carried the plague and were doing just fine, but when they jumped shipped and infected humans, they wiped out millions in the 14th century. It's the same with the influenza virus, and other viruses. Their goal is to multiply within their host for a while and then spread. Sometimes though, killing your host and exposing its fluids to other organisms is the best way to migrate.
|
Why do auctioneers need to speak the way they do? It seems like 99% incomprehensible gibberish with some numbers in between.
|
They want to tap into your impulse buying habit. They don't want you to think which your mind can't do as well when it's trying to process the auctioneer. It's also a way to increase the speed and thereby increase the pressure on you.
|
Because you don't win an auction by being the last bidder. You win an auction by being the highest bidder.
|
Was each sperm different from the one that created me or would the next sperm created an entirely different looking person?
|
Our DNA is composed of 23 pairs of chromosomes (one chromosome of each pair from each of your parents). Each gamete (sperm and egg) has one half of the individual's 23 chromosome pairs (so it has one complete *half* of the human genome). But *which* half of each pair is completely random. Without taking mutation into account, there are 8,388,604 possible, genetically-distinct sperm from a single male. The average ejaculate contains 39 million sperm, so there were (statistically speaking) roughly 4 other sperm that could have also fertilized the egg to become you. A total of five out of 39 *million*. There are also 8,388,604 possible eggs. So if you do the math, one pair of adults can have 70,368,744,177,644 (70 trillion) potential *genetically different* children.
|
This happens frequently in other branches of life. This is essentially the definition of self-pollination in plants. Plants produce both sperm and the egg in order to produce seeds. The offspring would NOT be a clone of the mother. Rather, the mother would be the mother AND the father. So, if you were to draw Punnett square for something, say blood type, and the mother were type AB then the Punnett square would look like the right image here: _URL_0_ As you can see, the offspring would have a 50% chance of having the same blood type, a 25% chance of being type A, and a 25% chance of being type B. Now extrapolate this over the entire genome of the offspring and you can see that there's a great amount of genetic variety that the offspring could be, although it would be at high risk of contracting any genetic disease that the mother has. TL;DR. It wouldn't be a clone. It would just be much more similar to the mother than if it had 2 separate parents.
|
How many gravity assists would Voyager 2 have to make off of Jupiter to completely deorbit it into the Sun?
|
It can't slow down Jupiter alone, because it can't take up so much angular momentum. But we can make many Voyager probes each doing a single fly-by before escaping the solar system very fast. Jupiter's escape velocity is 60 km/s. We can send probes at ~ 30 km/s to Jupiter and let them get deflected by something like a 90 degree angle. There is some optimum but I don't know where exactly. For a probe mass of 800 kg, this changes the momentum by 30 km/s \* sqrt(2) \* 800 kg = 34,000,000 kg m/s. If we do the process fast compared to Jupiter's orbital speed, or always do it at apohelion, we need to change its momentum by (mass of Jupiter)\*(orbital velocity), plugging in numbers we get [7\*10^23](_URL_1_) probes, with a total combined mass [close to Saturn](_URL_0_). A bit lower if you optimize the probe approach speed. On the other hand, getting this mass to this speed will need some propellant as well.
|
Current tech isn't actually much better, Voyager just took advantage of a rare alignment of planets to do a bunch of gravity assists. There are some ways we could improve, though. My favorite is ion engines powered by actual fission reactors producing tens of kilowatts, instead of merely a few hundred watts from radioisotope thermal generators. Unfortunately there are political barriers to investing in that. Another idea is solar sails - you drop into a very low orbit and pick up some speed from the ~~solar wind~~ radiation pressure. Mass would be very limited, though, and I'm not sure if it would be effective at actually escaping the solar system. Edit: Thanks Olog, you're right, the radiation pressure is more significant.
|
Why can't we synthesize Gasoline?
|
We can synthesize gasoline just fine. It's just much cheaper to pump oil out of the ground and refine it.
|
We can. There are companies that can synthesize oil and gasoline from other products. It just isn't anywhere near cost effective at this point and it doesn't solve any of the major problems associated with using fossil fuel.
|
What is the difference between nuclear fission and fusion?
|
Fission is the splitting of big atoms (Plutonium, Uranium etc.) in to smaller ones, releasing energy in the process. This happens naturally all the time in in different amounts, but we refine the material and bring pieces together to produce a lot of energy. Fusion is the smashing together of small atoms (starting with Hydrogen, the smallest) to make larger ones, which also releases energy. This only happens naturally in extreme conditions, the core of stars such as our Sun. Scientists are trying to do this here on Earth, to give us an essentially limitless energy source.
|
Fission will occur if a nucleus can decrease its energy by splitting into smaller constituents, and fusion will occur if nuclei can reduce their energy by combining. If a fission process releases energy, the fusion process obtained by running this in reverse does *not* release energy. Likewise, if a fusion process releases energy, the fission process obtained by running this in reverse does *not* release energy. The nuclei of heavier elements can release energy via fission, while the nuclei of light elements can release energy by fusing.
|
What does the red cross mean next to the points in a reddit comment?
|
It means that voting on the comment was controversial, meaning there were both a good number of upvotes as well as downvotes to arrive at that score.
|
Basically you post to both subreddits, one then the other. That's what people mean when they say cross post (or X-Post in the title, which they type).
|
How well do books popularizing some of the more "complicated" sciences (ie, QM and string theory) correctly portray these subjects?
|
Disregarding the inappropriateness of "complicated" (I agree strongly with foretopsail), no. They don't. They give you a very superficial view of these topics. Reading one of these books gives you about as much understanding about fundamental physics as reading National Geographic gives you about ecology. If it doesn't have math in it, you're not really learning anything about physics.
|
I don't think there is such a thing. Contemporary string theory moves at a very fast pace and is not really in contact with popularizers. It's also become a very vast and specialized subject. It would be very awkward to try and cram the last 16 years of string research into a popsci book. Sadly, or thankfully, things aren't as easy as when "the Elegant Universe" came out. Now, if instead of being a layman you have a physics background, you could try Witten's recent "What every physicist should now about string theory", which is a paper but also has an associated [lecture](_URL_0_). But even then, that's only the basics of strings, just interpreted in a modern perspective.
|
Why do grapefruits and grapefruit juice interact so much with so many types of medications?
|
Grapefruit juice inhibits an enzyme (CYP3A4) that is very important in metabolizing many different medications. So when you drink it, the enzyme function is reduced, and less drug gets metabolized (and so it stays in the body longer than normally, which leads to it accumulating) and can result in toxicity of the drug. Hope that helps!
|
A compound in the grapefruit, bergamottin, stops an enzyme from being released. This enzyme breaks down a lot of medications in the blood, so if it isn't being released than the level of the drug could either be higher than the intended dose or be active for longer than it's intended to be.
|
What is a Home Owners Association?
|
To some, it is the devil; to others it is a safety net. HOA's are when a community has a committee that sets and enforces rules for the home-owners in said community. They may enforce rules like which colors can be used to paint a home , how much or little you can decorate outside, even enforce things like yard upkeep. Some buildings, like condos, have HOA's that are in charge of hiring maintenance vendors, paying building staff, and legal issues associated with the building and its tenants. I personally vow to never again own a property with an HOA because i don't miss kindergarten (and they all act like children).
|
In the UK at least: * Banks are (usually) owned by their shareholders - their ultimate aim is to make money for the shareholders * Building societies are owned by their members, that is anyone who has savings, mortgages or possibly some other products with them. If you're a member of a building society, you can attend members meetings, and might be asked to vote on certain elements of how the society is run. The fact that they're not trying to generate a profit for shareholders might mean that the building society can offer lower mortgage rates than a bank would, for instance.
|
What is "processing power" and the difference between i3, i5, and i7 processors.
|
Everything your computer does is the result of lots of small and simple instructions (e.g. put this value x in memory location y, or add x to y and store the value in z). The processor reads these instructions, and carries them out. When people talk about processing power, they are referring to how quickly the computer is able to read and carry out these instructions.
|
The desktop version? Hyperthreading. I7 processors are able to run 2 distinct tasks per core, whereas an I5 can only do one. This is a bit of an oversimplification. You can read about the concept here: _URL_0_
|
What does "ex machina" mean?
|
Deus Ex Machina is when something totally unexpected and out of the blue comes and rescues our hero in the last second. Like, an almost forgotten character shoots them in the back just as they're about to shoot - or the Eagles in Lord of The Rings. It's a common enough trope. All looks lost, and suddenly - look! The writer pulls something out of their rectum and the day is saved. It's lazy writing since it's obvious the writer painted the character into a corner they now can't get them out of, and have to write in a weird and lazy rescue.
|
In ancient Greek plays, tragedies often ended with a God descending from heaven (lowered by a machine, of course) and bringing closure to the plot. Hence the saying Deus ex Machina (or God from the machine). It is usually used when someone or something out of the blue brings a storyline to an end which would not have been possible otherwise. Example: In the final matrix movie, Neo makes a pact with one of the machines to kill Agent Smith. Without the help from that machine, this would not have happened and nothing in the film up to that point indicates that such an event was even a possibility. Note that the thing interfering in the plot line does not have to be divine or a machine to be called a Deus ex Machina, it simply needs to bring about an improbable change in the story.
|
How do the police find callers that are too incoherent to give their location? If they have some method of independently finding you, then why don't they just do that every time, instead of wasting time asking you?
|
In the USA, the emergency operator (police) knows where you are, 95% of the time, as soon as they answer the call, especially if you're on a "landline" (not a mobile phone). Even with a mobile phone, they can usually find you pretty quickly. Log into Google Maps with your mobile phone. See? Your phone knows where it is. Of course, older mobile phones and phones that block information are a bit more difficult to locate. If an emergency operator asks for your location, they are just making sure that there is nothing that is causing them to see a false location. Also, they are trying to keep you occupied and on the phone with them. Emergency operators are trained to "chit-chat" (not the correct thing to say, but you get the idea) until someone physically arrives.
|
Assuming you aren't talking about the mechanics of obtaining name/address to give to the police - how can they ignore a call? Someone calls them and says "I hear gunshots at xyz address!" they can't just say "lolnope!", they have to go. There's plenty of hate for police lately, but you can't expect them to go in against a potential shooter without minimising their own risk, which often means increasing the risk of the victim. So, victim is in for a bad time.
|
Why do people have 'a drink' when having conversations?
|
Psychological analgesia. It makes one more comfortable and lowers the stress of small talk. Plus it opens the door to share a vice and bond over getting blind drunk together after business is settled.
|
It lowers your inhibition level. You know that little voice that tells you when something is a bad idea? Booze shuts that voice down.
|
If humans originated in Africa, how could they reach Iceland/Australia etc. without modern technology?
|
Boat is the right answer. They reached Australia by traveling down from the Malay peninsula and through the Indonesian archipelago, possibly through Papua New Guinea. Look up the map, each sea voyage is quite short. They reached Greenland from North America, which is also a shortish voyage. [Wikipedia]( _URL_2_) had lots to say about this topic.
|
[National Geographic](_URL_0_): "*Most paleoanthropologists and geneticists agree that modern humans arose some 200,000 years ago in Africa. The earliest modern human fossils were found in Omo Kibish, Ethiopia. Sites in Israel hold the earliest evidence of modern humans outside Africa, but that group went no farther, dying out about 90,000 years ago.*" [Human Origins Project](_URL_1_) and the [Genografic](_URL_2_) will probably tell us more. Nothing else so far.
|
Why are there so many different cryptocurrencies?
|
For one thing, starting a new one that is just the same as an existing one with a different name takes almost no effort since they're all (I think, certainly most) open source. Then there are different motivations: * The get-rich-quick scheme: if you ran ran bitcoin mining on your home PC for a few weeks back when it just started, you'd be a millionaire today. So why not start a new one where you can be the very first miner, and hope it will somehow become popular? * Shits and giggles: Dogecoin. * It's a genuinely interesting and also very hyped concept, so many programmers want to experiment with it. * Some are serious attempts to add features or fix problems that Bitcoin can't address because it has to stay compatible with the existing Blockchain. Ethereum is probably the one with the most feature innovation.
|
Because people believe others will continue to buy them and their value will increase. It's effectively an asset bubble. They have an underlying value as a currency, but the *vast* majority of the increase in their price is just speculation.
|
Where in the United States are there the least amount of amphibians?
|
There are [*no*](_URL_0_) frogs in [Barrow, Alaska](_URL_1_) (pop: 4,212). Of course, the average low in February is −23.1 Fahrenheit, and the average high in July is 46.7. Oh, and the sun sets in mid-November and doesn't come back up until late January. And then the sun rises in early May and doesn't set until early August.
|
You might be better off asking in /r/animalid or /r/species.
|
Where does our body heat come from? What actually generates the physical heat that our body needs to maintain itself?
|
Basically, every single cell of the human body is constantly undergoing all sorts of chemical reactions, some of which produce heat as a byproduct (those which burn energy for example). By burning energy, I mean breaking down energy sources, which produces heat as a byproduct. This heat is transferred into blood, making our blood act as a sort of heat sink, pooling all the heat we're generating at any one time. Thermoreceptors (endings of sensory nerves which can detect heat), transmit this information to hypothalamus within the brain. The hypothalamus then sends signals throughout the body to adjust itself to dissipate this heat (like sweating, flattening hair on skin, etc.).
|
\[Mammals break glucose down into H20 and CO2 to make ATP \(adenosine triphosphate\).\]\([_URL_1_](_URL_0_)\) The chemical process is exothermic; it produces heat. That heat is either needed or not by the body at the moment. If the body is already warm enough, the heat will be released in the breath, through skin pores and sweat. If the body needs more heat at the moment, it will be routed to the internal organs. The hypothalamus is making all these decisions and giving commands via a cocktail of hormones.
|
During Alexander's campaigns, by whom did the conquered people say they were being conquered? Alexander's armies, the Macedonians, the Greeks? or maybe none of the above?
|
I don’t know of any sources contemporary with the invasion itself, but the general term used in Asia from pre-Hellenistic to modern times to refer to both the Greeks proper and to the Macedonian successor-states was “Ionian” (or words derived from it—like “Yauna” in Persian, “Yavana” in Sanskrit, and “Yavan” in Hebrew). Ionia was the Greek-speaking region on the Aegean coast of modern Turkey that was subject to the Persian Empire; the Ionians therefore traveled widely throughout the empire and became known as far as India. So “Ionian” became the common term for all Greek-speakers, and was used throughout the east to refer to Alexander and his successors in the Hellenistic era.
|
"Hellenistic" normally refers to the time after Alexander the Great conquests. The it refers more to the areas conquered by Alexander than to Greece proper, that his, modern Turkey, Siria, Iraq, Lebanon, Egypt, Israel, Jordan. In those countries a a big portion of the upper class were of macedon or greek descent, and the rest were the local elites that were co-opted. Both tended to adopt and adapt the culture of the conquerors.
|
Why don’t airplane oxygen masks inflate?
|
They will inflate only if the pressure of the oxygen line flowing to the mask is greater than the cabin air pressure. This will happen if there if there is a decompression at cruising altitude. At lower altitudes, the outside air pressure is higher, and the bag on the mask won't inflate. In the event of a loss in cabin pressure, there probably isn't time for a physics lesson and a math problem, so the flight attendants tell you that the mask may not inflate, so that you won't think that yours is broken.
|
This is to do with the flow rate of air into your lungs. Say I put on a standard face mask which is attached to a supply of 100% oxygen. I will get 100% oxygen into my lungs right? Wrong. The amount of oxygen you actually receive will depend on the flow rate of the oxygen source (from a standard hospital wall outlet this will be about 15l/min) compared to the flow rate you draw into your lungs from your own inspiratory effort - if stressed this can be 80l/min or more. So you are drawing in far more gas than the oxygen supply is giving you and so room air is entrained into your inhaled gas mixture diluting the pure oxygen. In most scenarios a face mask will deliver around 35% oxygen despite being connected to a 100% O2 supply because of this mechanism. The bag gives a small reservoir of pure O2 that gives a bit of compensation for high inspiratory flow rates. However in the setting of a crashing plane people's inpsiratory flow rates will deflate the bag
|
Are there enough asteroids to make mars significantly bigger?
|
No, the mass of the entire asteroid belt is about half a percent that of Mars.
|
Yes, but no such object exists. [The largest asteroid is about one-ten thousandth the mass of the Earth.](_URL_0_) Something that big would be a planet in its own right.
|
What is in cough medicine that makes it taste SO dreadful?
|
The main active ingredient in over-the-counter cough syrups is a drug called [dextromethorphan](_URL_0_). It's an incredibly bitter chemical & there's not much that can be done to cover up the flavor. Other cough syrups with more ingredients (eg - NyQuil) have other drugs which are also pretty foul tasting. Like most drugs, they don't really want children getting into it & deciding that it tastes good & drinking the whole bottle, thinking it's Kool-Aid, so little effort has been put into actually trying to fix the flavor.
|
Well, there are two basic ways they work. With one type of medicine(Antitussives is the big person term), it makes you not want to cough, another (expectorants is the big person term) allows the stuff you cough up to slide down your throat like apple juice does. NyQuil also adds other stuff like tylenol that may make you feel even better.
|
If the moon is in "freefall" around the Earth, why does it not accelerate at 9.8m/s/s?
|
9.8m/s^2 is just the acceleration due to gravity near the surface of the earth. Further away from the earth the number is quite different (according to google the acceleration of the moon in its orbit is 0.0027 m/s^2 ). The moon is accelerating towards the earth at all times, but due its lateral velocity it doesn't actually fall to the surface. If this doesn't make sense check out [newton's cannonball](_URL_0_)
|
The force of gravity is dependent on the mass of the planet. Earth's mass makes it so that acceleration due to gravity is 9.8 m/s², but on the moon or a less massive planet it is less and on a more massive planet, it would be more.
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.