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6dmi82 | Physics | If a nuclear weapon creates an EMP, why didn't the planes dropping them in WWII experience it? | They did, but it was not noticed because the electronics of the time. A World War 2 aircraft radio operating at 48 volts/ 15 amps would be able to handle an extra amp of electricity with out harm. it is 5% overloaded meanwhile a modern radio with microcircuits operating at 0.0003 volts and 0.0001 amps would burn out with 1 amp added. it is 1,000% overloaded. | 5 |
kzf26j | Biology | Why do my eyes start to tear up when it’s windy or cold outside? | The wind drys out your eyes. The point if tears is to protect your eyes as well as lubricate it, so when your eyes dry up, you tear up in an attempt to restore that outer layer of moisture. | 2 |
63jtg3 | Culture | What is going on in Syria | Edit: Formatting, and including the second-to-last question. > How does Assad get away with using chemical weapons? After the gas use of 2013, it was and still is unclear who used it. There are indications that it was Assad, the IS, some other group or even the Turkish Government in a "false flag attack". Because it is so difficult to find out who did what in war (this is called "attribution"), it is hard to definitely prove who used the gas. Assad then agreed to have his gas destroyed. I have no idea how much actually was destroyed. Now there was a new gas attack. The US and its allies blame Assad, the Russians claim Assad's air forces accidentally blew up a Rebel gas storehouse. I have no idea which one is true. But the problem remains that there is no hard evidence that Assad used the gas. As long as there is no prove, you can't really do anything. Also, what could be done? The US could invade, remove him from power, basically Iraq 2.0. US leaves, IS takes over the ashes. Also, removing Assad would mean direct confrontation with Russia, immense costs, tens of housands of dead civilians (which feeds into IS propaganda) and many dead US soldiers. > And why are they using them on civilians and children? IF Assad uses them, then it's collateral damage. The rebels and terrorists don't use special military barracks or military buildings but set up in normal houses, schools, hospitals. Gas doesn't make a difference if it kills combattants or children.They are collaterals. > Who does USA back? Most easily, the Kurdish Peshmerga. They are the military of Kurdistan, an autonomous region of Iraq. They support the Kurdish resistance is Syria and get support in form of air support, supplies and training by the US. One of the main Kurdish forces in Syria is the YPG (People's Protection Unit). The YPG is the main force in the large alliance SDF (Syrian Democratic Forces) together with many ethnic and religious minorities, local militias, and moderate rebels. How powerful each of them are, how moderate, and how strong their chance to really establish a Syrian Democracy, I honestly can't tell. > I keep hearing about US drone strikes, who are they targeting? Islamist groups. Most notably IS, Al Quaeda, and their numerous sub-groups. The US does not directly attack Assad's forces or allies. > Why is Russia such a strong supporter of Syria? First Russia was an ally of Syria for a long time. Russia must show that they defend their allies, or nobody will want to ally with them. Then, Russia has its only Mediterranean military base in Syria. A new Syrian government would be pro-Western and close this base. The Russians would lose influence in the Mediterranean. Also, Putin uses foreign military operations to show strength to his followers. The Russian economy is hurting, but he followers can forgive him that when he shows strength and power. With the involvement, Russia feels like a cold-war super power again that keeps the West on the edge of their seats. So Putin profits domestically from it. Lastly, Qatar had and has plans to build an oil pipeline to Turkey and Europe. Such a pipleline would make Europe far less dependant on Russia for oil. This is especially why Assad refused this pipeline. A new pro-Western government might allow this pipeline, which would seriously limit Russia's influence in Europe. (There is also the [conspiracy] theory that refusing this pipeline is the reason why the West wants to remove Assad.) > Other than the war crimes, why do people hate Assad and why are they rebelling against him? Is he a bad leader or is it mostly religious reasons? Assad's regime, while secular and one of the better ones in the Middle East, was still a brutal dictatorship where you could disappear in a secret torture-prison. At the start of the Arab Spring in 2011, protests were mostly economic. The people asked for economic reforms because prices (especially food) were rising, unemployment was high, and the economy in general was in a bad shape. Assad's government promised many reforms and started some of them. They also pardoned a few opposition leaders. However, at the same time protests were brutally suppressed by police and later the military. What many consider the spark for the escalation of violence was in 2011 when 15 children were spraying anti-government graffiti on walls and were arrested and tortured for it. When the parents asked for the release of their children, they were allegedly told "Forget your children. If you really want your children, you should make more children. If you don't know how to make more children, we'll show you how to do it." When you get to this point, you kind of don't see an alternative no peaceful protests anymore. > Is the conflict nearing an end? Is there going to be a "winner" or truce anytime soon? I don't think so. Too many countries have in interest in a prolongued civil war (Russia, Turkey, Iran, Saudi-Arabia) and the opposition is too fractured. I would love to hope for and end and a free democratic future for the Syrian people's, but I'm afraid of just getting my heart broken. | 3 |
6ldjc3 | Biology | How do masochists feel pain? Is it the same? | Masochism is more of a symptom, there are a number of different mental conditions that can lead to masochistic behavior: * mixing pain with pleasure enhances the pleasure * crosswired tp sometimes feel pain as pleasure * feelings of low self worth, and that pain is deserved * feelings of submissiveness, and accepting pains as proof of their submission * difficulties with any emotional response, using pain to feel something they can control * accepting pain to prove their toughness and ability to reach a goal * past association of pain and abuse with pleasure, particularly sexual pleasure | 2 |
5n3pxu | Physics | If energy can neither be created nor destroyed; only converted, what energy is converted to kinetic energy of a pin that accelerates towards a magnet as a magnet approaches it (assuming level surface, of course) | Magnetic potential energy. The magnet and the pin (combined) have some energy just by existing and being far apart. When they move closer together this potential energy is converted to kinetic energy. When you pull them apart again, you're supplying kinetic energy which is then converted into potential energy. Note that often to simplify calculations, we say they have zero potential energy when they're really far apart, and negative potential energy when they're close together. | 2 |
ecwmu0 | Biology | How carsickness works | Your brain has motion sensors and it also collects information through your eyes. When those disagree, like you feel like you're moving when all the things around you are not, that's a problem. Because poisoning causes similar problems, your brain calls out "dump out the poison in the stomach". | 4 |
hx9wlj | Engineering | What are the different components of the sounds you hear when you turn on a car? | The first thing you hear is the starter motor trying to get the engine going, once that happens, next you hear the engine. What makes some cars quieter than others is mostly just sound deadening. Some cars have more of it than others, and depends on where it's placed. There's also intake and exhaust systems to consider, depending on what kind of muffler and resonator, it changes the sound of the car. | 2 |
n5x2q5 | Biology | What causes sugar cravings? Why after eating food or being satisfied do i always feel like having desert or think about sweets? Is this genetic or a habit? | It’s 100% habit. I remember reading something about scientists years ago encountering an at the time undiscovered tribe somewhere. When they gave them sweats they tried it an spit it out. Sweetness is something that the more you indulge in the more you need to get that same satisfaction. I remember the first time I tried sweet tea in the southern US thinking good God this is really really really sweet. So I think it’s safe to say it’s something you learn to like. | 1 |
idbmk3 | Technology | Why are phone screen still made in breakable glass? I broke mine yesterday and it occured to me that phone could be made of plexiglass or unbreakable glass or any other material than the weak material currently in use. Why is that? | They used to use plastic screens before capacitive touch screens were the thing. They used pressure touch screens. And those screens would get scratched and cloudy in no time at all and looked like shit. | 8 |
a7ldja | Biology | if the symptoms of being sick such as runny nose, fever etc. Is ur own immune system, what does the virus/germ itself actually do to your body? | Viruses usually just try to "reproduce". They do this by entering one of your cells and release some of their own DNA or RNA in your cell. The cell won't know the difference, and the things inside it which translate it into molecules will start to produce the stuff which the virus DNA/RNA describes. This depletes the cell's own resources and makes it producing more instances of the same virus,killing itself in the process. When the host cell dies, all the created viruses are released. Germs, I 'm net entirely sure, but these are single cell organisms, which like to devide themselves to reproduce. They need resources for that, so I think they just either take recourses from other cells in your body, or prevent resources from getting to other cells in your body by taking them for themselves. | 2 |
5nt5mk | Biology | What happens to a fit, pregnant mother's abdominal muscles during and after pregnancy? | Omg I am currently 31 weeks pregnant and I am obsessed with what's happening to my ab muscles!! Can't believe there's a post about it | 27 |
lk56cd | Other | Why are you always an considered an “addict” or “alcohol” even if you’ve been sober for years? | Because addiction doesn't just go away. You're just dormant or in remission. I know people who haven't had a drink in almost a year but they're still an alcoholic. If you were to slip you'd just start back at the same level you were at before. It's hard wired into your brain now. It's just the way our minds process addiction. | 4 |
9bzhrz | Physics | What is the proposed "heat death" of the universe? | Energy doesn't really like to be confined in one place. It much prefers to spread out as much as it can. In fact, this "spreading" of energy is what causes everything in our universe to happen. The heat death of the universe is essentially maximum "spread out-ness" of energy that the universe can possibly have. But once energy is spread out as much as it can be, it will not flow anymore and no more physical processes will happen after that. It's not that the universe ends, it's just that the universe would be a boring, static thing where everything is the same forever. | 2 |
9mts6i | Physics | When pouring a thick liquid (like honey) why is it giving a kind of a zigzag shape right before it touches down? | The viscosity prevents the stream from merging with the puddle you’re pouring it onto right away like with water, so as more comes down the stream, it essentially piles up and collapses as it becomes unstable, or “top heavy” within the stream | 2 |
j9i8ux | Biology | Why does heat (heating pads, drinking hot water, hot towels etc.) help soothes period pain:? | Your skin contains different types of nerves (neurones) that are able to detect different things. Some of these sensory neurones detect heat, others detect low temperatures, while others detect pain, or touch, to name a few. All of these neurones work in the same basic way - once they have detected something, they send an electrical signal to the spinal cord which is then passed onto a second neurone which travels up to the brain. Once there, it activates certain parts of the brain associated with a certain feeling (hot, cold, pain, etc.). However not all signals are equal. The pain signals are split into two main types; dull, aching pain (carried by C neurones) and sharp, acute pain (carried by A-Delta neurones). What's interesting is that C neurones also sense heat of warmth. The theory is that by providing a heat at a comfortable temperature, you activate the C neurones so they sense that you are warm. This essentially blocks the pain signal from being sent to the spinal cord, so it is never registered as pain in your brain. Instead, you trick your brain into thinking you’re just a bit warm (which isn’t painful). This is why heat is better for dull and achy pain than for sharp pain like when you just whack your head. There are ways around this too though, for example if you have ever rubbed an area of skin that you’ve just hurt and it feels better. This is because the signals coming from the neurones which detect touch are all activated, and get to the spinal cord, which helps to block out the painful signals. Think of it like two roads called A and B, both leading to the same town (the brain) but which have to merge first (at the spinal cord). If there are more cars on road A to begin with, then more of them are going to eventually make it to town. | 3 |
gexdsc | Economics | Why would farmers have to slaughter their cows and waste the meat if it isn’t in as high demand right now? Why not keep them alive or donate the meat? | I have butchered large animals, not cows but bison and elk. Getting the animal to a location to start processing is difficult. We used a front end loader. Hoisting a creature that is 1,500 lbs or more is a real chore, and without a decent hoist, it is all but impossible. So, let's say you have your cow up and hanging. You skin it. What are your plans with the skin? Is there a tannery close that could use it? Now comes the fun part. You have all sorts of parts - head and the brain, hooves and the offal - lungs, heart, liver, kidneys and the like. Edible, but highly unlikely anyone would want. This, btw, accounts for about 40-60 percent of the carcass. What to do with this? Okay. So now we have a hanging carcass. You need to split it. Industrial processors use specialized heavy duty chainsaws. More than likely, you may have a sawsall, and this is not big enough. Well, we got the carcass split. Now is not the time to break it down. It needs to hang for a while - we went two weeks. Do you have a cooler large enough? If you cannot see the issues by now, consider one more thing: Even if you manage to get the carcass ready to butcher, you cannot sell any of the meat. It has not been processed in a USDA approved facility. TL;DR - Breaking down a cow for steaks is much more involved than most think. | 17 |
6njw1v | Repost | If cancer is just your body's cells, how can it kill you? | If you've seen the Matrix Trilogy think of cancerous cells as Agent Smith, replicating uncontrollably until everything has been taken over by those cells and the body can't function anymore. | 2 |
5x2mxx | Physics | why does the Big Bang mark the beginning of time and space? How can nothing exist before that? | "Before the big bang" could be akin to "north of the north pole". Something nonsensical. For if time started with the big bang, then nothing could be "before" it. Most importantly, though, the big bang does *not* describe how the universe was created. It's a name for the rapid expansion of the universe from a very dense, very hot point in time. If we extrapolate the physics we know to such a point, they break down. Why? Because we have two kinds of physics which we don't know how to combine. We know the laws of quantum mechanics that accurately and reliably describe what happens on the smallest scale of things. We also have relativity that accurately and reliably describes how the universe as a whole or big parts of it work. However, those two sets of rules don't play together well. They just don't speak the same language. And we don't know how to translate the laws of quantum mechanics into the language of general relativity or vice versa. Now, at the time of the big bang, the universe was very small, smaller than a single atom. So at this point in time, it was at the same time a massive, relativistic thing and a miniscule quantum mechanical thing. And as of now, we have no way to describe this, as stated above. Therefore, there comes a point where our understanding of the universe, when going back through time, breaks down. That doesn't mean that the laws of physics broke down. It just means we can't express how they worked before the expansion made the universe big and cold enough to make a description of it that's seperated into quantum mechanics and relativistic objects sensible. Now, did the universe begin at the big bang? Possibly. In this case, "before the big bang" might be akin to "north of the north pole" - a nonsensical statement. However, it could also be that the big bang was a moment in time with minimal enthropy. If you think of time as a linear dimension, it would stretch to both sides of the point where the big bang is. Coming from one side enthropy would decrease until we are at the point of the big bang and going on to the other, it would increase. We perceive the passage of time as moving along this arrow in the direction of increasing enthropy. On a grand scale, though, such a universe would be eternal in both directions of time, into the future and into the past. Models for the universe exist that describe it as such and that are not self-refuting, so this cannot be ruled out. But at the end of the day, *we just don't know*. And in science, to say that you *don't* know is a great thing. It tells you where to continue to search and learn and to do science. | 3 |
6xfo1t | Culture | What is the difference between Traditional Chinese and Simplified? I recently saw that in the Steam Hardware Survey, Simplfied Chinese was almost sixty times more common than Traditional. What causes this and why do natives use Simplified? | Simplified is more common because thats what China uses. it was developed by the communist government of china in the 50s to make reading/writing easier and increase literacy. anyone who was educated in china since then has learned simplified. Traditional is...traditional. Its what chinese used to be before the PRC decided to simplify and is still used by Hong Kong and Taiwan. It is definitely harder to learn as there are more unique characters and some are much more complicated to write. [ ex. here is the character for dragon in both simplified and traditional]( URL_0 ). one is definitely easier to write than the other. most people who can read/write traditional can also read/write simplified too since its basically an easier version. | 4 |
63t0c0 | Culture | Queen Victoria ruled over one of the most powerful empires in history for almost a century. So why did it take until 1918 for women to be considered politically intelligent and allowed to vote? | In 1867, Lily Maxwell voted in a by-election in Manchester where regulations granted the right to all ratepayers, but overlooked the need to except women. Several more female property owners in Manchester followed suit, but the following year the loophole was plugged, and women’s suffrage was declared illegal. | 31 |
5xve3i | Repost | Why is our brain programmed to like sugar, salt and fat if it's bad for our health? | Actually.. On the ketogenic diet these are STILL the best fuels for our bodies and minds. I shit when I seen someone say that they weren't. Our bodies need 10,000 years to adjust genetically to any massive technological change like the agricultural boom we experienced which is how we've got shit loads of food on the shelves in stores and other madness. RIP. | 37 |
fd2yci | Physics | What makes a particular area, a perfect path way for Tornado's? I live in Nashville, and we just had a very devastating EF-3 Tornado over night that caused massive damage and lose of life, especially in the East Nashville, or Five Points area. URL_0 This article came up where 2 previous tornado's (1933 and 1998) had pathed into the same focal point, and I was wondering what about this area makes it perfect for tornado pathing? | Tornadoes reach thousands of feet high. Nothing on the ground really “attracts” them to follow a path. Things like hills and mountains and other large disruptive landscape features can certainly interrupt a rising, spinning column of air, especially if it formed at a lower elevation. And that in turn might mean that a certain topography - a certain landscape - might be more favorable for tornado formation, which in turn might sort of mean that some areas might see more of them, but that’s not the same thing as the question. Tornadoes generally move from west to east because that is the way fronts/storms usually move. And depending on what time of year it is, the general direction of storms will be more specific in a particular spot, like for example maybe most summer thunderstorms in the upper Midwest are forming along cold fronts sweeping from west-southwest to East-northeast. Given that some of those storms might spawn tornadoes, it’s likely that many paths will have roughly parallel or even similar paths. It is odd that two of those historical paths have a lot of overlap, but that is how randomness works sometimes. It’s not necessarily a sign that the path there is actually attracting tornadoes or more favorable to them. | 5 |
mjopc8 | Engineering | how come exploding a bomb intentionally by the bomb squad is safer than itself exploding? Wouldn’t the external explosion trigger the bomb and now you would have to deal with the sum of both bombs? | The point of the "bomb squad's" involvement is to control when it explodes, to shield it if possible, evacuate people, to some extent nullify the damage. | 3 |
b6aadh | Biology | Why do wisdom teeth exist and why do they grow sideways? | Long ago your teeth would fall out. The wisdom teeth were needed. Now dentists save your teeth so they can charge you to pull out your built in replacements. | 5 |
7gl8iz | Biology | Why are antibiotics so effective but at the same time bad for us? | When you are sick the bad bacteria causes you problems. Solution. Bomb it with antibiotics. Problem. We have millions of good helpful bacteria co-existing with us that also get killed with those antibiotics. So you destroy the bad and good bacteria without prejudice. Lucky for us our good bacteria has lived with us for a while and can usually bounce back to a healthy population. | 2 |
72217s | Other | Why does having "good lawyers" get people off with lesser punishments even if they're obviously guilty? | Because a good lawyer knows how the law works, knows how the judges work, and knows how the prosecutor's office works. Even if you're guilty as hell a good lawyer can pick apart every little inconsistency and "what if" in the state's case and introduce doubt. Prosecutors know that, and if they don't *really* want your ass for something serious they'll just offer a deal rather than spend the money and time fighting your lawyers. | 4 |
gh1muk | Biology | What energy does the brain "collect" when we sleep? We recharge our energy when we sleep, what does this actually mean? Why are we getting tired from staying up late? That kind of energy. | While we are awake, there is a chemical that builds up in our brains called adenosine. This chemical makes us feel sleepy. Caffeine works by blocking our brain from feeling the chemical. When we sleep, our brains are able to clear it out. | 2 |
63hdi6 | Physics | Growing up my mother always told me to never start a pot of boiling water from hot tap water only cold. What's the logic behind that if any? | It's simply because in some water systems your hot tap sits in a tank (in the loft usually) whereas the cold tap is 'fresh' water. source: have asked lots of old people why they say this | 31 |
l9rapp | Engineering | Why does it take longer for the last 10-20% of a (EV) battery to charge compared to the bottom ranges? | Think about filling up a bucket, but if you spill too much water the bucket explodes violently. Sure, you can go fast at first but then at the top you better slow down. | 2 |
ilmsit | Technology | Why are some programming languages so complicated while others are so simple? For example, the "hello world" program in Python: `print("Hello world")` The "hello world" program in C++: `#include < iostream > ` `int main() {` `std::cout < < "Hello world";` `return 0;` `}` Why is Python so user friendly while C++ is not? Or am I missing something here? | What you're missing is that: 1. Python was designed to be user friendly, C++ was designed to add features to C which was designed to closely align to machine code 2. There were 20 years of computing advancements between C and Python 3. C/C++ is more powerful than Python 4. That C++ code will compile to an executable of like, a couple KiloBytes, the Python code several MegaBytes 5. The C++ code will execute in a fraction of the time of the Python code | 5 |
67ni0f | Physics | Why did 9/11 jumpers fall unconscious or die before they hit the ground, how come most people can sky dive with no problems? | There is no reason to believe this is true. While it is possible someone would faint from stress until such an extreme circumstance, this is not a given. It sounds more like a comforting story people tell so they can believe those people suffered less. | 5 |
ktqjeu | Biology | If skin is a watertight barrier, how do medicinal creams work? | It's watertight, but some substances that are not water can penetrate the skin. A famous example is dimethylmercury, which can penetrate not just the skin but a rubber glove on top of it, with [fatal results]( URL_0 ). | 3 |
l05v0c | Biology | Would health or body weight outcomes differ if you: a) Eat one slice of pie every day, year round, or b) eat 7 slices of pie on one day each week, every week, year round. Would the same be true for alcohol? Is regular consumption of unhealthy food/drink better or worse than periodic bingeing, holding average consumption amount equal? Had to look up spelling of bingeing/binging. Seems they're both acceptable. | Nutrition wise: It would be different, because your body adjusts based on how much it needs to work at the time. But that said, the difference would be so small it may not even be worth paying attention to. Dental: Well, yeah, because you're exposing your teeth to the sugar 7 days a week rather than just one. | 4 |
i8osy4 | Other | Why are most baked goods baked at 350 degrees Fahrenheit | Prior to modern ovens people cooked on wood stoves inside their homes. Recipes back then called for generalized temperatures like a warm oven or a hot oven. When adjustable electric and gas stoves were invented they measured the temperature of a wood stove for comparison. 350F was a medium oven, 400F was a hot oven. 350F is also the ideal temperature for the Maillard reaction, which is when food starts to color and brown generating flavor but before it just burns. People new about this in Wood Ovens as well, and used a medium oven of roughly 350F to achieve this. | 1 |
l7ckr5 | Economics | Stock Market Megathread There's a lot going on in the stock market this week and both ELI5 and Reddit in general are inundated with questions about it. This is an opportunity to ask for explanations for concepts related to the stock market. All other questions related to the stock market will be removed and users directed here. How does buying and selling stocks work? What is short selling? What is a short squeeze? What is stock manipulation? [What is a hedge fund?]( URL_0 ) What other questions about the stock market do you have? In this thread, top-level comments (direct replies to this topic) are allowed to be questions related to these topics as well as explanations. Remember to follow all other rules, and discussions unrelated to these topics will be removed. **Please refrain as much as possible from speculating on recent and current events.** By all means, talk about what has happened, but this is not the place to talk about what will happen next, speculate about whether stocks will rise or fall, whether someone broke any particular law, and what the legal ramifications will be. Explanations should be restricted to an objective look at the mechanics behind the stock market. EDIT: It should go without saying (but we'll say it anyway) that any trading you do in stocks is at your own risk. **ELI5 is not the appropriate place to ask for or provide advice on stock buy, selling, or trading.** | How can the normal people involved in this become rich? Once one person sells the stocks for a high price they get a lot of money, but wouldnt that mean the price will fall? And so the other people wouldnt get that much money? | 489 |
71o338 | Economics | Why is the economy of Puerto Rico in such tough shape? It is a US territory, uses the dollar and goods and people can pass freely to the US. Shouldn't it be more like Florida as a major tourist and vacation spot? | It's in tough shape because it's caught halfway between being a country and a state with all the negatives of each overwhelming them. For instance, Puerto Rico depends on Congress to bail them out if they start struggling. This is bad because congress often gets locked up and fights over nonsense meaning Puerto Rico's budget woes often ends with it being thrown under a bus. Especially made worse given that they have ZERO representation in the US congress. At the same time it gets all the abusive corporate behavior of the US but with little to no ability to defend themselves. Puerto Rico remaining a protectorate is only in corporate best interests at this point as they're heavily exploited by quite a few industries. They need to either be their own country or be a state if they want to do well, at their current pace they're only set to continue to self destruct. | 2 |
6mvjtk | Mathematics | If kids only learn the common core method of basic math (addition, subtraction, multiplication, division), does that groundwork prepare them adequately for more advanced math? What happens when they get to Algebra? | Yes. You're talking about the method of learning *arithmetic.* Algebra is a very different subject, and doesn't rely on how you learned arithmetic. You'll still need to take pre-algebra and then algebra, just like anyone else. | 4 |
nevt7b | Engineering | Why do the rpm in a manual transmission fall when changing gears? When changing gears, the gear ratio will change, but this would only effect the output rpm from the transmission. The input rpm from the engine is independent of the gear ratio. Does the tachometer measure the input or output rpm to/from the transmission? If it measures the input, from the crankshaft before the transmission, why would the rpm fall? I can see why it would fall due to frictional losses from not acceleration, But not from changing the gear ratio. | The RPM measures the engine rotations, not the transmission. But the RPM goes lower because you are going at a speed, lets say 30MPH, and change from lets say 2nd gear into 3rd gear, which is geared higher. So initially, to stay at the same speed, your engine has lower RPMs to be at 30MPH in 3rd gear than it had in 2nd gear. Of course, you can step on the gas to go back up to the same RPM you had before, but you'll be going faster. The input RPM is not fully independent of the gear ratio. Since the power goes through the transmission and ends up in your drive wheels, the RPM of the engine does depend on gear ratio. The wheels will turn faster at higher gears. | 2 |
eolbst | Biology | Why do people who have high blood pressure not donate blood, have some removed? Given that high blood pressure is a bad thing why is the treatment for it simply removing blood which would lower the pressure? | Your body manufactures new blood cells all the time. That is one thing that bone marrow does. So it would not actually help because you get new blood within a short time. | 3 |
5uyg99 | Culture | Why is there no security at train stations when there are so much security at airports? | because the tsa at the airport was a knee jerk reaction to 9/11 to give the public the appearance of safety and waste a shitload of tax payer money... much like the lying orange muppet's wall will be. | 38 |
d12z5q | Other | How do actors portray dead characters in movies? Do they actually sit there and just hold their breath? | Yep. For extended/dangerous scenes (or if it’s cheaper to create one in case the actor’s per-day rate is more expensive), a highly realistic dummy is created. (See *The Autopsy of Jane Doe*, Zod’s body in *Batman v. Superman* or Kristen Stewart’s frozen body in *Zathura.*) | 1 |
lddr60 | Chemistry | How does wax evaporate with such a small amount of heat in a candle, and how is breathing in wax not unhealthy? | The flame has a temperature of a few hundred degrees C, enough to vaporize wax that's close to it. When do you breathe in was vapour? It's burnt up to make the flame. All that left is carbon dioxide, water vapour and some soot from incomplete combustion, that last is what's glowing in the heat of the flame to make the candlelight. | 3 |
a6muwx | Technology | what is the difference between disk capacity and density with a SSD? I'm trying to upgrade my system and have a vague idea. Want to clarify before I buy. | Capacity is what you really want, that's how much total storage the drive provides Density is about how much storage we can fit in one flash chip. Higher density chips enable higher capacity drives in the same size, or drives with the same capacity but fewer chips Density matters in the long run, it's what has enabled us to go from 256 GB 2.5" SSDs to 2 TB 2.5" SSDs; but when you're building a machine you only care about what you can get right now and that's capacity | 1 |
7qxcrt | Technology | Why do LED lights look jittery or like they're strobing when you look at them quickly? | They're often dimmed using PWM(pulse-width modulation) in cheap applications. Basically they're turned on and off really quickly and by changing the ratio of on time to off time you can change how bright it appears to your eyes. The problem with this is that when they move through your vision(you turn your head or they move) or you wave something in front of them you'll get weird results because its not on all the time. There is a distinct image that only appears at specific locations on your retina instead of being a blurry smear across it like your brain expects from a continuous source. Good applications will instead provide constant power and control how much current is flowing through the LED. Providing constant power means they aren't turning on and off and don't leave you with the weird jittering effect. | 15 |
l2wfp9 | Mathematics | Why are complex numbers so important? | we live in a 3 dimensional world. The number line is a 1 dimensional line. Complex numbers bring numbers into the 2nd and 3rd dimension. and the 4th dimension! Theres a great series on youtube about complex numbers. URL_0 its 13 short videos. i recommend watching them all. it gives you a much better understanding than a classroom gives you. | 5 |
8jk9j1 | Other | Why do digital artists make their artworks grey so then add colours? | It's to help with lighting and values. If it looks good B/W it'll look good in colour (in theory). Sometimes it doesn't work out that way but it does help you learn lighting, form etc quicker without having to worry about throwing colour into it as well. | 2 |
8r86xb | Other | the ENTIRE Geneva Convention. What is it all about, and what are the ‘rules’? | because some things are so bad, that you don't want other people to do them to you. Or because we decided that some ways of killing each other was to cruel and may cause more damage to civilians ( chemical weapons, landmines, nukes and radiation) Men don't kick each other in the balls when they fight, because they don't want to get kicked in the balls themself. | 1 |
hocsp2 | Chemistry | Why does the weed smell linger in the air (outside) for significantly longer than cigarette smell? | Pot smoke has [thiols]( URL_0 ) in it (the same things found in skunk smell), and humans are super good at detecting thiols in the air. Sharks can smell blood in 1 part per million, humans can smell thiols in 10 parts per billion. That's 100x better. & #x200B; edit: changed a number | 1 |
664iv4 | Biology | Why are hand dryers in public restrooms considered more hygienic than paper towels? Having forced air blowing germs all over the place doesn't seem very hygienic at all. | It turns out that you are correct. Not only do they blow germs from outside the blower... What happens when someplace is dark, warm, and moist? Mold grows. So you're getting mold spores and waste from INSIDE the dryer on your hands, too. URL_0 | 2 |
7tpm7c | Physics | What is a death bubble? I'm reading "This idea is brilliant" and they mention death bubbles in physics eventually destroying all of an intergalactic society given enough time. What causes these bubbles? Are they stable? | > What causes these bubbles? Are they stable? We don't know that they *can* exist or if they are stable, but the general idea is that empty space as we know it has an energy level associated with it. Even without anything in a given region of space there are fields and an inherent energy to the vacuum itself. This is the general basis behind theories about "tapping zero-point energy"; the "zero point" is the lowest possible energy level which, surprisingly, is not actually zero. Now the "death bubble" concept comes up when we consider that entropy generally states that things tend toward the lowest energy level possible as they are more stable. Conceptually then it may be possible that our current universe is not in the lowest possible energy level and could somehow decay into a lower energy state. How or why this could happen we don't know, but if it did we would expect the fabric of the universe to change into something fundamentally different, expanding outward in all directions at the speed of light. When this region passed over an existing area of space the fundamental particles making up everything would cease to be, converting into something else. Even the fundamental forces of our universe would likely be changed along with the existing dimensions. The result would be that anything in that region of space, advanced intelligent alien species or not, would be utterly destroyed. There would be no way to even see it coming as it would propagate at the speed of light if not faster. | 3 |
hgaw9e | Biology | Why are baby lullabies always played at such high pitches and why do babies seem to like the high pitch songs? | It sounds less like a threat, sounds similar to their own voices, makes them pay attention longer than most adult voices (because they dont sound "right" to babies) and the "happy" tone sounds more attractive than the "meh" tone that adult's voices have. Remenber, babies dont understand what we are saying and dont have the finesse to see the diference in tones in adults voices, and "baby talk" tends to be super exagerated. They just know it sounds happy and friendly and that means this person is a friend. | 4 |
c98p8b | Biology | Why do most living organism in the deepest portion of the ocean are TRANSLUCENT? | Clear skin is easier for biology to make than opaque skin, but if an animal on the surface had opaque skin, their organs would get sunburn and they'd die. Deep sea animals never see the sun and can't be hurt by sunburn, so evolution makes them stop bothering with opaque skin. | 2 |
5z72h3 | Biology | Why is an uneven object, such as a framed picture on the wall, unsettling to humans? | Because we've all learned about gravity the hard way. Something off-kilter like that looks unstable. That is, it looks like it won't stay put and may fall. Now we tend to notice that without thinking and it grabs our attention. But then we stop to really look and think about it and go "Oh, it's fine. It's just a crooked picture. It won't fall." But then a few seconds later when we STOP actively thinking about it, our automatic-brain says "OMG! That's not stable! It might fall! You should check it out!" The constant distraction is what makes it annoying because your not-thinking part of you keeps tapping you on the shoulder to tell you about that thing you already know is fine. So you just fix the picture and then it stops grabbing your attention over and over again. That's one theory, anyway. | 2 |
fgcg3n | Chemistry | Why do big storms seem to happen at night and clear up during the day? | The heating and cooling of the air due to direct sunlight affects some storms' ability to form. Think of condensation on a drink. The cool surface of the class/bottle/can draws moisture out of the air making the container sweat. The same can happen with the air. The cooling due to the removal of direct sunlight can allow the moisture already in the air to (further) condense, increasing the chance for rain. | 1 |
5lo6gr | Culture | Why does so much of American youth culture originate from the African-American culture? | A lot of culture comes from the cities. And after we developed the suburbs, white people left the cities en-mass. Black people were not often given loans to buy houses in the suburbs and even if they had the money a lot of people wouldn't sell to them. So the cities ended up being really disproportionately segregated. When people are in close contact they tend to develop culture faster. So for a period of time there white people got really good at lawn care and black people got really good at throwing parties. A good example is the recent explosion in '*nerd culture*'. Before the internet this minority was sublimated by the broader culture. But with the rise of the internet, nerds were able to interact. Their culture evolved fast and became pretty interesting and distinct. And now it is acting on the broader culture just like black urban culture has in the past. | 2 |
5nsbu1 | Culture | All guns shoot, so why are shotguns in particular called shotguns? | Because shotguns shoot a large number of smaller pellets, frequently called [shot]( URL_0 ). That name comes from an early manufacturing process using [shot towers]( URL_1 ), which were tall towers from which molten lead was dripped and via air resistance and surface tension they would form into spherical pellets and land in water to cool. | 3 |
m62167 | Biology | Why do people get all warm and fuzzy inside when they are around someone they like? | Nervousness could be a reaction to arousal. In response, the body unconsciously performs functions that would elicit the effect of blushing. IE body uses vasodilators that control where blood will enter, in this case towards the head. So the face will appear more redder in color because of increased blood flow. | 1 |
61nc7i | Physics | If solar winds are powerful enough to rip Mars of it atmosphere, then how does our technology survive? | The main issue that Mars has is a lack of a strong magnetosphere. Earth is very protected from solar winds and energetic particles because it has a strong magnetic field. | 2 |
8w5tm7 | Other | I live in the low desert of California where it regularly reaches 105° during summer. Why did 12 people in Canada die from overheating in 93° heat? I'm referring to this article URL_0 I should also mention that my city has a large homeless population (not something I'm proud of) but they're outside in 105° - 110° and yet we don't have 12 people dying from overheating in a few weeks time. I also lived in Phoenix, Arizona for a time. Again, significant homeless population in 110° - 118° heat, and there aren't this many deaths. Do humans acclimate to their climate over time? Is it genetic? A combination of the two? | Only 50% of Canadian homes report having air conditioning in them. Someone who is vulnerable to heat, particularly the elderly, may have been able to get by just fine without it until a heat wave pushed them over the edge. The elderly usually make up most of such deaths because they are infirm due to their age as well as often engaging in behaviors which increase the risk such as being dehydrated. The heat could push other health problems over the edge into killing them. | 6 |
dl2bt7 | Other | why do SWAT teams use rams but firefighters use axes if the purpose of both tools is breaking through doors? One of these tools has to be more efficient than the other, so why don’t both use the same tool? | Maybe weight and ease of use. Fire fighters have lots of bulky gear on, heat resistant coat, helmet, oxygen tank, face mask, etc. An axe is lighter and can be used to make a hole in the door/wall with less force than a ram. If there is an obstacle behind the door, a ram won't be able to knock the door away from the frame and is less useful in trying to punch a hole in a door made of heavier matierals. | 14 |
7cg4h0 | Other | Why does FM stations starts at 86 to 110 rather than other numbers? (Atleast where im from, SEA) | Because those are the frequencies the local government(s) have assigned for commercial radio stations. Other frequencies are used for other things, and in other parts of the world commercial radio uses different ranges, too. | 11 |
hc8y0x | Other | How could people back in the day wear so much clothes during the summer? | They certainly did have problems with the heat, but it has also been hotter lately because of things like climate change. Also, not everyone wore that much in the summer. Summer dresses, for example, were made to be more breathable. | 2 |
7ns9io | Biology | When your body is submerged in cold water, it feels freezing at first, then starts to feel warmer and warmer. When your body is exposed to cold air, it feels okay at first, then gets colder and colder. What causes this phenomenon? | I'm no expert, but I think it has to do with body heat. In the water, your body heat and the temperature of the water find an equilibrium where both are at the same temperature, whereas in the air, it's always moving so it cools your body while your body heat doesn't have time to affect the air temperature. | 3 |
atjo5f | Biology | What is the reason that the sound changes when yawning while listening to music? | Your [ear drum]( URL_0 ) blocks your ear canal completely, and separates a chamber in your middle ear from the outside. You have a channel, the Eustachian Tube, that links this chamber to your throat, that opens when you yawn / open your jaw wide. So what happens is your middle ear chamber may be pressurized, which will make your ear drum tighter, and thus make it receive and vibrate to sounds differently. And when you yawn you re-establish atmospheric pressure (equal pressure) on both sides of your ear drum membrane. | 1 |
6aq5mi | Culture | why is english seen as the "universal" language? I was just thinking about this, why is it that whenever there is a need to translate a language its always to english. A better way to put this would be to ask why is english the universal language even though its not the most widely spoken language? | The "universal language" or "Lingua Franca" is the language used by the most powerful nation of a time period for politics and trade. During the pre-Roman era that was Greek, during the Roman era it was Latin (with some Greek holding on). Later French became the language of dominance in politics and then when the British Empire boomed English took over. The US traded places with the UK after WWII and since this was the era that communication boomed English was well established as being dominant for trade and politics. | 4 |
7ofv98 | Technology | How do contactless cards generate their RFiD signal? Surely there needs to be a source of energy to generate this signal but how come I don't need to charge my card | The reader hits it with a pulse which gives it enough energy to send a response with, this makes the bases big and lets the tags be tiny. Its a combination of wireless communication and wireless charging | 1 |
5onhm1 | Culture | Why is Judaism considered as a race of people AND a religion while hundreds of other regions do not have a race of people associated with them? Jewish people have distinguishable physical features, stereotypes, etc to them but many other regions have no such thing. For example there's not really a 'race' of catholic people. This question may also apply to other religions such as Islam. | It should be noted that there is an entire "tribe" of Jews known as Beta Israel, or Ethiopian Jews. As the name may suggest, they have very different features than, say, Polish Jews. And yet they are still considered fully Jewish and many have immigrated to Israel. | 40 |
875it7 | Chemistry | How do large food/drink franchises maintain perfect taste-matching around the world, all the time? Wouldn’t things like seasonal conditions affect coffee production and flavor profile, for say, Starbucks? Or the life of a certain farm animal vs. another affect the steaks at, say, Outback Steakhouse? | Those big franchises change their tastes according to area they operate in. Coca cola does taste differently across the world. So does mcdo and any other you could name. | 1 |
mvxnym | Other | why is math so commonly the subject that every child has hated? What separates math from the rest of the subjects? | More than any other subject Mathematics is about a right and a wrong answer. Even Science is more about developing the critical thinking skills required to come to said answer, while Mathematics is almost exclusively about just which answers are wrong and which are right with minimal element of 'discovering' the subject. Kids don't like to just be told 'this is right' and 'this is wrong'. Hell, *people* don't like this, which is why conspiracies get so much truck: it's often seen as admirable or good to question what you've been told and some adults take that as carte blanche to question all the way to first principles even though they have no understanding of the subject matter. | 7 |
b9wrov | Biology | How do cells communicate through cell signals if at the most basic levels they're just a bunch of bonded atoms? | The fact that matter is made of atoms has no impact on communication in fact the phone I am using to reply is made of atoms. Those atoms use electricity to communicate with each other ultimately resulting in this reply. Extending this backwards toward cells. Cells use chemical signals to communicate with the specialist receptors to trigger various effects. Imagine that those chemicals are specialized keys and the receptors are specially locks. When the right key enters the right lock, the cell replies in a predictable way producing the desired effect. | 1 |
hltgyz | Biology | Why do humans show teeth when they're happy and want to seem friendly while animals do it to intimidate? | I saw a British educational series on human gestures that showed chimps have a "fear face" where they show submission and fear by displaying their teeth. And in humans, it is not a far leap to take the fear face and turn it into a smile that says "I am not a threat to you." | 17 |
8feukw | Chemistry | Why do some clear liquids turn foggy when mixed together? Working at a bar, have always wondered why clear (pilsner) beer and clear apple cider turn foggy when mixed together. I'm sure there are plenty other examples. How is this, and why are substances clear or foggy in the first place? | There are two ways this very often occurs: either it forms millions of tiny bubbles (like with your drinks, because they form or release a gas) or it forms millions of tiny solid particles (called precipitate) because of their chemistry. There are other ways that this happens, but these two ways are the most common. Substances are clear because of the arrangement of the electrons in the chemicals. The chemicals that interfere very little get part of the light spectrum absorbed when light passes through, so it looks colored. If the chemicals interfere basically not at all (like water) it looks clear. Things get distorted through liquid for the same reason lens do: they change light's direction. | 2 |
70iihd | Biology | How do I decide to use heat vs ice on an injury? | Depends on the injury and when you are treating it. For a muscle injury (for example a muscle strain), the immediate treatment is to follow REST (Rest, Ice, Compression, Elevation). The ice (along with R, C, E) is used to slow blood flow to the site and reduce swelling. After some time, it's time to treat the injury through rehabilitation (eg physiotherapy). At this time it is common to use heat to relax the injured muscle and warm it up in preparation for stretching/massage/strengthening/etc. For a different kind of injury, heat is used immediately. For example, for puncture stings by marine animals (stone fish, scorpion fish, etc) part of the recommended treatment is to soak in very hot (but not so hot it causes a burn) water. | 1 |
dd4g1j | Technology | How does a speaker know what sound to produce from a series of 1 and 0s? I understand that there is magnet and it vibrates to the current. But how does it actually convert? | It doesnt. And audio program converts the audio file into a sort of rough wave form by sampling. Imagine you draw a sound wave as a sinewave. An analog sound has infinite steps in a sine wave. Since that is hard for computers to do, it measures the height of the wave. How many times the wave is measured determines the audio quality. This is also called sampling rate. The output is a reconstructed sine wave. This is an alternating current. When the current passes through the spool in the speaker it gets a magnetic field. Because the spool is next to a magnet it either gets attracted or pushed away. When the current changes direction the magnetic poles of the spool change sides. This creates a vibrating Motion in the spool, which we hear as sound. | 3 |
ckoa0v | Physics | How does a hot and deserty country like Egypt have such a high humidity? I'm in Cairo right now and I noticed the humidity is incredibly high. In fact, I took a water bottle from the refrigerator out and it was soaking wet in a matter of minutes. For a place in the largest desert in the world and being so incredibly hot this time of year (just short of 40°C) it's quite strange. You'd think such high humidity would contribute to better vegetation also, but nope. How is it so humid? | Are you sure the humidity is that high or are you just use to a very low humidity? A quick google says the humidity there is only 33%, which is quite low when many places are at 80%+ right now. That said, it does border nothing but water on roughly half the country, so that is a pretty big factor to humidity. Look at other countries surrounded by water and you'll notice much higher humidity than Egypt typically has (only up to about 60% from what I could find). | 2 |
hkl3fh | Chemistry | What IS the Elephant's Foot, exactly? | I assume you are referring to the Chernobyl power plant. When the Chernobyl accident occurred and the reactor blew up, the fuel from the reactor was no longer being cooled. This fuel continued to heat up until it melted. The melted fuel dribbled down from the ruined reactor into a puddle in the basement of the power plant, and that puddle flowed down into the sub-basement levels through broken pipes. The elephant's foot is composed of "corium", which is a mixture of melted reactor fuel, other melted metals (the structure of the reactor), as well as melted sand and concrete which the molten fuel encountered. The corium is intensely radioactive because it contains spent (used) nuclear reactor fuel. The corium is extremely radioactive, but its radioactivity is decreasing exponentially. When it was first created it was so radioactive that it generated enough heat to melt concrete, but now it is only a few degrees above room temperature. Scientists can spend brief periods of time (less than a minute) near the corium before they have to leave, to avoid getting a dangerous dose of radioactivity. The safe time limit is increasing slowly. Radiation is like microscopic bullets. When you are near a radioactive object, tiny particles shoot through you, and these particles can leave a path of destruction. Your body is able to repair this kind of damage to a certain extent, but if too much damage occurs, you develop radiation poisoning, as all the damaged cells break down simultaneously and overwhelm your body's ability to repair itself. Radiation generally doesn't kill someone instantly. Absorbing a high dose will make your body extra susceptible to cancer. An even larger does will result in burns, hair loss, anemia, and digestive problems. Finally, a large enough does will result in severe internal and external burning followed by coma and death within hours. I'm not sure what the dose off of the elephant's foot was a few weeks after the accident, but it is quite possible that a lethal dose could be absorbed within a few seconds of being in the same room. The elephant's foot wasn't discovered until several years after the accident, and when it was found it was still dangerous enough that scientists collecting samples had to sprint into and out of the room in only a handful of seconds. | 3 |
lwoixo | Biology | If exercise is so good for your mental health and takes advantage of your brain's reward system, why do people forget to do it? Shouldn't it be highly addicting purely for its own sake? | Exercise actually can be addicting! This is because exercise releases endorphins which make us feel happy and 'high'. However, it is also a lengthy process. It takes advantage of our brain's reward systm in the long term. Say you were to start an excerise programme today - along with you taking care of nutrition and other health-related issues - you probably wouldn't see results for quite some time. I'm no expert and can give no numbers in this regard. A shorter path to a feeling of happiness is better because, well, it's shorter. Eating a donut is an instant reward and takes quicker advantage of our brain reward system. Buy donut + eat donut = feel good. Work out + eat well + committment = results you have to work to maintain. It's just a longer and more mentally taxing project. | 5 |
6bibgh | Mathematics | Why is Multiplication called an elementary operation? Wikipedia says that multiplication and addition are both elementary operations, which sort of implies they are different operations, but it also says that multiplication is "repeated addition." Is multiplication truly its own operation, or is it just a more efficient way to add things together? | Elementary operations does not have to be atomic. In fact it is possible to define addition based on more simple operations like the increment operation. Elementary operations are the four operations used in elementary arithmetic which is a simplified subset of arithmetic that is the foundation of modern math. It is mostly used for educational purposes and as such the "elementary" means that it is something that everyone should know. | 4 |
eqh3vk | Other | why are companies so keen on recruiting externally instead of promoting from within? | Any answer is bound to be a bit generalized. And every reason will have it's promoters and detractors. Promoting someone internally doesn't automatically make someone qualified enough to perform in the new role. First, there is a risk that the promotion "doesn't work" - now you have a situation where there is a gap to fill on top of someone not doing well in their new position. Second, looking outside allows a company to possibly hire someone with a proven record in the open position - less need to invest in training and possibly bringing some new ability to the organization as a whole. In a rapidly growing company, hiring externally is also preferred sometimes. First, it possibly grows capability (mentioned earlier). Second many companies that started small hired for talent that may have been what the company needed then usually with a more generalist attitude and able to "get things done" possibly not in building systemic capability, specialized subject matter expertise or capable in management. As a company matures and grows, it typically needs more system oriented processes (consistent, scalable, appropriate checks/balances) and less outcome based processes (go for the diving catch, do what it takes) - all reasons to look outside. I have had many conversations mentoring young professionals (especially technical/functional) that "management" is a profession not simply career progression. I usually suggest that they think really hard about what it takes to switch professions - what they like about what they're doing now and what they will be facing as a manager. Money, responsibility, recognition and challenge are all reasons to aspire to management but it is not to their benefit to take on managerial responsibility and hate it from day one. | 6 |
bvr2bi | Technology | the C computer language compiler was written in C. How did it get compiled if there was no C compiler until it was written? | The first C compiler was written in B. That sounds like a joke, I know, but it's true. C was originally called "NB" for "New B." Dennis Ritchie wrote up the history of C for his website at Bell Labs, which you can read here: URL_0 | 1 |
ark94h | Other | What makes emo music emo? | So it has to do with the overall key of the music and the lyrics set to them. Most keys that emo songs are in are minor keys meaning in a chord you would have a root note we’ll call this (1), a third that is flat (or a half step lower) we’ll call this (3b) and a fifth (5). This is a very basic structure for a minor chord. Every scale has 8 notes in it 1,2,3,4,5,6,7,8 (this is where the 1,3,5 comes from) or “do re mi fa sol la ti do”. But when you have the key of a song in minor it sets up that feeling of “emo” you’re talking about. Minor keys sound sad, major keys sound happy. Those other songs that don’t seem to be emo are set in a major key most likely. Which makes them sound not as angsty and emo. So a major chord would have a (1), (3- not flat) and a (5). Edit- spelling & punctuation | 1 |
aaw8px | Other | Why would deer hunters wear camouflage if they have to also wear an orange vest to avoid being shot by other hunters? Wouldn’t the vest just give their position away to the deer? | I haven’t seen anyone comment this yet, but usually you only wear the orange vest until you get into the stand. After that you can take it off. | 12 |
91ewzh | Other | Why are movie directors often blamed for bad movies, when they usually have very little (if any) to do with the story and screenplay? | The director actually has a lot do with the story and screenplay. If they're no good, in most cases the director can ask for a rewrite. The director is the artistic manager of the film - they are in charge of bringing the movie to life. They are involved in every step of making the movie, including choosing the screenplay, casting the actors, filming the scenes and then editing the film. | 2 |
jr8pm6 | Engineering | Why are boat propellers on the back and plane propellers on the front? This is obviously based on the assumption that the principle is the same for both craft. If that is true then what is the benefit of their respective locations? I understand that based on their current designs why it may be “convenient” but it seems like a “pushing” vs “pulling” debate would result in a universal trait/answer for both craft. | There are planes with pusher props on their backs. On water vehicles I'd assume you'd prefer the turning instability caused by having the thrust center at the back This is also why combat jets use vectored rear propulsion, apart from the obvious aero benefits. | 1 |
dc9d6x | Biology | Why is there a higher chance for miscarriage or deformities I the baby when the parents are more closely related by blood? | Everyone has all sorts of recessive genes that would create all sorts of problems. It's very unlikely that any random person on the street has the many of the same recessive traits as you. However, if you were to have a kid with your identical twin, it's *very* likely that you would both contribute the bad recessive trait, resulting in a deleterious effect on the kid. The more closely you are related, the more likely you are to share bad recessive traits. | 3 |
9xvwi4 | Biology | Where do blood goes after a person dies naturally or out of sickness? | After death the blood just congeals in the arteries and veins because the heart has stopped pushing it around the body. Unless the person dies because of blood loss, in that case the blood goes everywhere. Edit: congeals means it turns into clumps, almost like very thick mud. | 2 |
5qd0dl | Biology | Why is it entirely possible to fall asleep while listening to music, but very difficult to fall asleep while listening to someone snore? | I think it's subjective; if a sound can lull you into a sense of security and distract you from thoughts that would otherwise keep you awake then it'll be easier to fall asleep. Anything that helps you disconnect from the day without stimulating you would likely help you sleep. I personally can't sleep with music playing, but I can with my wife snoring. Other favorites include rain, a ticking clock, night traffic, and the sound of someone mowing their lawn a few gardens away. | 2 |
6kygr1 | Chemistry | If your clothes aren't dried properly, why do they go sour/smell bad? This has happened to us all, right? And now that the weather is so humid and sticky my clothes are taking longer to dry on the clothes horse than normal. So, my question is this: Why do your clothes start to smell sour/bad when they take to long to dry or are left sitting damp for a while? EDIT: Unreal response from people regarding this. Didn't expect to get such a huge and varying reaction. A few things: - I'm not looking for a solution - I'm interested to why this happens. Bacteria Poo is my favourite so far. - Yes, a clothes horse is a real thing. Maybe it's a UK term, but it's essentially a multi-story rigid washing line that sits in your house. (credit to the dude who posted Gandalf.) Thanks, Glenn | I hang dry everything and I don't have this problem. If clothes are left in a pile or a dark, damp place, the smell of mold will continue. Also, those spores will jump to anything else in the area, especially anything that has been worn. All those items will need to be treated and washed. Source: personal experience | 18 |
8x0l3p | Physics | My wife says that whether an object sinks or floats in water is determined by the size of the container, not just object density. Help me I say floating is simply a product of relative density (as long as object has enough room and water to float in to begin with) She says that whether or not something floats is determined by the density but ALSO the volume and/or depth of water in the container. E.g. if I put an egg in the sink bowl it will sink and she says that it might float if I put it in a full pint glass as there's 'more depth water to make it float' Assuming there is at least enough water to submerge the object in, can you help me explain why she's wrong? | Who cares about explaining buoyancy? If your eggs float, they’ve gone bad. Your wife is eating bad eggs. | 8 |
adajco | Physics | Why do some materials resonate at certain frequencies when they is sound playing around them? I was recently playing at an orchestral concert and I noticed that my viola(string instrument) was vibrating on certain notes when I was not playing while my chair vibrated on different notes. What’s the reason for this? | It’s called a resonant frequency. Every object has a frequency that the molecules are vibrating at. If you then expose it to other frequencies, the waves can either diminish each other, cancel each other out, or add together to amplify the frequency. This is called the resonant frequency of the object. Basically if you expose an object to its resonant frequency, it vibrates more than normal. Google it. It’s the same phenomenon at play when a loud noise at the correct pitch (frequency) can shatter a wine glass. The noise is causing a huge amplification in resonance (vibration) within the glass, causing it to shatter. | 2 |
6mlmt0 | Biology | Why do we "hallucinate" while reading? | Uh...do we? I visualize what I'm reading in my head but that's about it. | 2 |
5lrapu | Biology | What causes mental fatigue while studying? | When you look at the activity needed for the brain to study and learn new material, it is a pretty large machine that needs to be running. The core component of the nervous system in general, and the brain in particular, is the neuron or nerve cell, the “brain cells” of popular language. A neuron is an electrically excitable cell that processes and transmits information by electro-chemical signalling. Unlike other cells, neurons never divide, and neither do they die off to be replaced by new ones. By the same token, they usually cannot be replaced after being lost, although there are a few exceptions. The average human brain has about 100 billion neurons (ELI5: nerve cells) and many more neuroglia (ELI5: supporters). Each neuron may be connected to up to 10,000 other neurons, passing signals to each other via as many as 1,000 trillion synaptic connections, equivalent to a computer with a 1 trillion bit per second processor. So - your computer(brain) has a LOT to do while internalizing new information, and this activity - like any other activity - causes fatigue. | 1 |
7m5swl | Repost | Why does metal spark in the microwave? | Metal objects spark in microwave ovens because those objects have peaks and points where static charge can accumulate and spark out. If you could somehow get something metal in a microwave where the metal thing was both perfectly round and perfectly smooth, there would then be (presumably) nowhere on the outside of the metal thing for charge to accumulate. However, this doesn't mean there would be no accumulation at all. It would simply not be on the surface. (Physics Reddit, please correct me if I'm wrong.) | 1 |
9npu87 | Biology | How come our own "bad" odors (body odor, flatulence, bowel movements) don't affect us as much as someone else's? | It is actually a survival instinct, the everyday smells that you smell get shut off from your brain to make it easier to detect new foreign smells and be aware that something is around. I believe it was around the time we came out of the trees and the amount of predators as well as the amount of prey we started going after increased that we developed it. | 4 |
f575lo | Technology | How do speakers work when you increase or decrease the sound? | Speakers work by using an electric signal to move a magnet, which moves a cone, which vibrates the air, which you perceive as sound The speed at which the signal cycles determines the frequency, or the tone. The amount of power determines how hard the magnet is pulled, which determines how hard the air is vibrated, and how loud it is | 1 |
6ku32a | Biology | Why do we put our heels down first when we wear shoes, but our toes first when we are barefoot? | This difference only applies to running and can be attributed to the excessive padding in most running shoes (shoes created after the 1970s). With the added padding, runners could strike the ground with their heel first with and feel no pain. This is an easier running form to have since it doesn't require any calf muscle, but over time can cause havoc on the feet and shins. instead, land near the toes allows the muscles in the feet and calf to absorb the impact from running. The Arch in the foot plays a big role in this act. For those that are flat footed, note that arches can build with exercise and that your shoe size with shrink as this happens. Source: [Born to Run]( URL_0 ), and long time runner. | 3 |
b4e07g | Economics | How do companies like SpaceX and Boeing that close deals worth $100M+ get paid? Do they receive a check or wire transfer? | Yes. Literally as simple as wire transfers. That’s how monetary transactions occur. In a practical sense, that $100M generally would not be in one lump payment though. It would be progress payment, such as: I give you $50M to start and $50M when you give me the first plane etc. | 1 |
5p1n8q | Biology | How does Alberta not have any rats? Alberta is the largest inhabited area in the world without any rats. How'd that happen? | Rats didn't arrive in Alberta until the early 1900s, and Alberta was proactive about killing them early on. When the first infestations were found, Alberta passed legislation to eradicate the rats currently living there and prevent new infestations. The harsh climate means that rats can only realistically survive near human settlements, so Alberta's rural layout meant that they were able to limit the movement of rats into the area by poisoning or destroying abandoned farmhouses and other areas that were ideal for rats to move into. Any new rat infestations were targeted with rat poison or fumigation to eradicate them, and that continues today. The Alberta government has more info on the history of the program [here]( URL_0 ). | 1 |
8zxn2m | Economics | How do wealthy people manage finances? How does investing work for someone who is in the 1%? What about the .0001%? I assume they have financial advisors taking care of this for them, but what techniques/institutions do people with tens of millions of dollars use that normal people don't? What does Jeff Bezos do with his cool 150 billion to make it grow (not that he needs to, obviously). | I work with a lot of ultra high net worth clients. Ultra high net worth is loosely defined as $30 million investable assets not including home, cars, collectibles etc. A quick google shows there’s about 226,450 UHNW people in the world, about .003% of the world’s population. $30 million really isn’t even all that high in my humble opinion. That’s high enough for them to think they are hot shit but really not much different in the investing world than like $1m, just more zeroes. At that level and above you get into more hedge funds and private equity investments, or buying and selling whole businesses rather than just a few shares of them. There’s a range between people above retail investors buying the S & P and before a handful of world class billionaires like Bezos that fall into this range. Guys like Buffet and Bezos have almost their whole net worth in one company (which in buffet’s case is invested in a whole bunch of other companies but you get the idea). They can’t move their wealth around very easily without causing a ruckus in the markets. At pretty much any investing level above your IRA and 401k, you are going to want to focus on long term tax efficiency and planning, which is a big part of what I do. Taxes can be a huge drag on your portfolio’s performance so tax efficient asset allocation and estate planning are key. At any level, you are going to want to keep your costs low and spending under control within your means, because you’d be surprised how fast you can blow a few tens of millions of dollars if you aren’t careful. Sorry for the wall of text, just some streamof thought to somewhat answer your question. | 4 |
cfc6ru | Other | How does a Night Guard (a hard chunk of plastic) prevent clenching damage to teeth? I mean, I'm still clenching all night. It's not tooth on tooth but I'm still biting down crazy hard on a hard object. Just curious how this one works. | Hardness is what's at factor here. A substance with a higher hardness than another will damage the softer item, without being damaged itself. For example, diamond will cut through glass without being cut itself, because diamond has a higher hardness. Plastic is much less hard than your teeth. Your teeth will damage the guard rather than each other, and the plastic isn't hard enough to damage your teeth itself (it will instead just deform). | 2 |