id stringlengths 5 6 | input stringlengths 3 301 | output list | meta null |
|---|---|---|---|
6bhwj7 | why are radio waves preferred for long distance communication? | [
{
"answer": "Nice properties of radio waves:\n\n1) The go through walls, unless they are made of metal.\n\n2) They are bent by the upper layers of the atmosphere, so a radio message can go from the US to Europe.\n\n3) Very sensitive receivers are mass produced at very low cost, so that only a very small part of... | null |
4v9hrp | Why will an outside observer never see someone cross the event horizon of a black hole? | [
{
"answer": "Because you see things by receiving the light they emit that then travels from them to you. Any light emitted by the object inside the event horizon cannot reach you because it cannot get out. All light you'll ever receive will have been emitted by the body outise the horizon.",
"provenance": n... | null |
170k1e | why do current comedy t.v shows, like 2-1/2 men, still use background audience laughter | [
{
"answer": "Because audiences are used to it.\n\nTV shows were largely adapted from stage performances, where the performers had to account for audience reaction. When those same viewers watched TV shows, they seemed *off* until someone got the idea of adding the laughter back in.\n\nThe practice has continue... | null |
15dqa5 | Are food related allergies amongst children rising, or are we just getting better at diagnosing now? | [
{
"answer": "Increased hygiene and use of antibiotics reduce the diversity of the microorganisms living in and on us (human microbiome).\n\nIt is *very likely* that we develop more allergies because of this (at least compared to, say, 1850).\n\nThe lesson:\n\n* Getting dirty might even benefit your kids\n* Pres... | null |
2lqao7 | what is the difference between a soft taco and a burrito? | [
{
"answer": "a soft taco is open like a hard taco, a burrito is wrapped, and usually has a sauce of some sort on top of it.",
"provenance": null
},
{
"answer": "it really depends on if you wrap it up entirely or not. if you leave it open, it's a soft taco. if it's wrapped up then it's a burrito. ... | null |
1wx9p2 | How efficient are drinking fountains? | [
{
"answer": "There is a balance between efficient and sanitary and ergonomic. A drinking fountain can be really efficient if you had to lock lips with it. But I wouldn't want to be the second person in line. Definitely not the 100th person. \n\nA drinking fountain that shot short bursts, kind of like those sin... | null |
u3rme | How come only wet hair can stick to the shower wall? And when it dries up, it doesn't fall off? | [
{
"answer": "I'll answer this question in two parts:\nFirstly water has high surface tension, when something is forcing to it spread out (the hair in this case) it will want to bind to a surface, in this instance the wall.\nTo answer your second question; your hair has grease and dirt in it (no offence), this m... | null |
ki9sq | what does "creative destruction" mean (economics)? | [
{
"answer": "When Apple started selling the iPhone, everyone bought one and said: \"Hey, this is awesome! It does so much more, and looks so much better, than my Blackberry.\" Everyone was happy... except RIM, who makes Blackberries.\n\nThat was an act of creative destruction on Apple's part. They created somet... | null |
3mk95x | if the world trade centers were destroyed by the government what would be the benifit? | [
{
"answer": "THEORETICALLY: It would cause a public uproar that would lead to a uniting of patriotism and a outcry for war. War means a lot of money for a lot of businesses, and up to a point, increases favor and confidence in the government who is responding. They said the same thing about FDR and Pearl Harbor... | null |
9dt3rc | how does chromatography work? | [
{
"answer": "You pass a mixture through a column which is made of some sort of medium. The parts of the mixture which are attracted to the medium will go through at a slower rate. The parts that don't like the medium will speed through. When the mixture comes out of the column it will be separated. The fast... | null |
vhw3f | How much does the centrifugal force of the earth affect between the equator and the north/south pole when you jump. | [
{
"answer": "At the equator the centrifugal acceleration term is 0.03392 m/s^2 . At either pole it's 0. On the other hand, the gravitational acceleration term varies by only 0.6% from the pole to the equator, so let's assume it's 9.81 m/s^2 and constant. So at a pole if you jump it's 9.81m/s^2, at the equator ... | null |
gi6jl | Why isn't the Oort Cloud belt-shaped? | [
{
"answer": "I am no expert on [angular momentum](_URL_0_) and more importantly, the [conservation of angular momentum](_URL_0_#Conservation_of_angular_momentum) but it would seem logical that all the stuff at the outer edges of a cloud will be least likely to sweep together to form a disc. The trajectories of ... | null |
3cn60j | why can't you be paralyzed from only the waist up? | [
{
"answer": "You're paralyzed based on where the nerve is severed on the spine. Basically, everything below that spot is paralyzed. It doesn't work the opposite way.",
"provenance": null
},
{
"answer": "The nerves go down from your brain. Everything below the break in the nerve stops responding ... | null |
32pzoc | Is there any scientific basis in the adage "Opposites attract"? | [
{
"answer": "There is evidence, but it's to the contrary. [Assortative mating](_URL_1_), where individuals mate more with those that share traits (geno- or phenotypic) than those who don't. See also, [homophily](_URL_0_).\n\nThe one big exception is sex/gender, where disassortative is more common: There are far... | null |
gd0le | X-ray Diffraction with Lasers | [
{
"answer": "Yes coherent x-ray sources such as free electron lasers (like the LCLS at SLAC) are able to resolve much greater detail in the fine structure around Bragg peaks. The most useful way to consider the information content of this finely detailed low angle scattering is to consider its location in recip... | null |
4o5pz8 | why is organic food called 'organic'? | [
{
"answer": "The word stems from a 1940 book suggesting that the whole farm is a living organism. [Details.](_URL_0_)\n\nThis is as opposed to an industrial and synthetic-chemical-based approach to farming, which treats the farm more like a factory or a machine.",
"provenance": null
},
{
"answer": n... | null |
534ke6 | why do musicians and bodyguards use that hollow earpiece from the neck to ear instead of just regular earpiece? | [
{
"answer": "Musicians often wear a custom molded ear piece that both offers hearing protection and plays music into their ear so they get feedback of the music or singing. A lot of old rockers have significant hearing loss because they didn't wear hearing protection on tour.\n\nAs for protective details like b... | null |
6dfaqo | if oil is hydrophobic, then why are you supposed to apply body oil when your skin is damp? wouldn't absorption rates increase if your skin was dry? | [
{
"answer": "It's more to prevent moisture from leaving your body while it is warm and your pores are open. You don't really absorb the body lotion, it sits on top of the skin and helps prevent dryness.\n\nAlso, they are formulated to help blend in with the skin (which is a bunch of cells surrounded by a hydro... | null |
w6nne | What is the status of Germany's WWII debt? | [
{
"answer": "Disclaimer: I'm no expert on this and I'm not sure what exactly is meant by \"Germany's WWII debt\". I think this is about the pre-war German debts. Germany defaulted on a lot of debt (15 billion Mark; at least some of it incurred by the Versailles treaty) in the 1930ies. The debtors lost their mon... | null |
9iyxk7 | why is cosby's sentence 3-10 years? why isn't it a definitive number? | [
{
"answer": "I've never seen an actual sentence carry a range like that. Ordinarily, sentences are indeed definite numbers of years or months and each particular crime will carry a sentence range within which the sentence will fall. For instance conviction of a particular crime carries a sentemce of 3 to 10 yea... | null |
22cqbw | How long did it take for messages to be delivered on the medieval age? | [
{
"answer": "I'm sorry, but according to reddit there's one comment, however I can't see it. Is it hidden or has it been removed?",
"provenance": null
},
{
"answer": "Please don't say primitive. That's derogatory. An essential part of life for the vast majority of people that have ever existed was... | null |
2yskf2 | Why can some animals (like rats for example) be inbred with no problems but when humans do it we get all, sorts of problems? | [
{
"answer": "While I dont know for sure but I believe even in humans, it takes a few generations before the chance of something happening is big enough for something to happen. At least in rats and humans their is a greater chance of them breeding with an outside gene line before defects happen.",
"provenan... | null |
1mera8 | Do we know what Georgy Zhukov's thought of the other best-remembered generals from WWII? | [
{
"answer": "Hmmm... seems topical for me...\n\nIn my readings, I haven't come across too many direct statements from Georgy on his thoughts as to the military prowess of his Western counterparts. What little there is, he was mostly praising, but that is to be expected perhaps, seeing as they were obviously ver... | null |
39z9vn | if bernie sanders' political positions reflect what americans think, why is he such an underdog for the presidency? | [
{
"answer": "Many Americans share the same *ideals*, such as low-cost college, affordable healthcare, expanded social security. But Sanders position is extremely deficient in ways to *pay* for this that would be agreeable to all but a very slim minority on the political left.",
"provenance": null
},
{
... | null |
650u6g | why do humans not sneeze in high pressure situations, such as sports? | [
{
"answer": "I used to play on a sports team. I sneezed back then. Your premise is incorrect. Can you offer more information, such as where you got this idea?\n\nUpdate: I just sneezed at work, despite being under a lot of pressure from my boss. ",
"provenance": null
},
{
"answer": null,
"proven... | null |
29zdx6 | 18th-century battle formations | [
{
"answer": "I think it's best that I have a master post for me to reference for this.\n\nFirst, I'll address your criticism of the formation. The Charleville Model 1777 (which was used by Americans due to French supply) had a generally 83% accuracy rating in a perfect field with perfect weather at fifty meters... | null |
nofun | Shisha vs. Cigarettes and the nicotine | [
{
"answer": "Forgive my ignorance, but is there anyway to smoke Shisha without some sort of device (traditionally a Hookah)? I have always heard about the debate between whether cigarettes or Hookah was worse for you but it usually focused around the difference in mechanics (or lack there of), not the differen... | null |
2j9ugy | How many times has Russia been invaded in winter? Why? | [
{
"answer": "It's not that armies set off for Russia in the dead of winter, rather invasion plans that centered on quick defeat were never realized and armies became bogged down as winter set in. Napoleon and Hitler launched their campaigns in June, but of course their dreams of swift victory were never realiz... | null |
3kkw83 | Who was the first painter to manage a photorealistic style? | [
{
"answer": "Buonarroti was probably the most consistent and most photo realistic. His sculptures were probably also the most realistic. But the Greeks were generally the first to accurately depict the human representation. Unfortunately the only mediums to survive since 500 A.D. were their statues. \n\nHowever... | null |
3cwsey | why a company like nestlè can take water out of a state/province for $2.25 per million litres, only to sell it back at a profit. who is letting this happen? | [
{
"answer": "This is an explanation not just for this specific case but for large companies in general. These companies create jobs, and will also be paying taxes on a myriad of things. Sometimes the government will therefore sweeten the pot by reducing certain costs, knowing full well that overall they and the... | null |
binkxl | why do songs sometimes sound at a different pitch when the volume is low? | [
{
"answer": "Something harmonically important is not loud enough to establish the tonal center. Likely the bass. Without the bass notes (the chord roots), the tonal center can easily become ambiguous. Sometimes the remaining musical parts, such as guitar, piano, melody, etc., can still define the key and tonal ... | null |
27rvor | the simulation theory. | [
{
"answer": "Well, really simply explained The Simulation Theory states that we (as in the whole universe) is just a simulation in someone’s supercomputer, like the Sims or the Matrix. The idea is that somewhere outside this supercomputer there is a person/entity that perhaps wanted to know how the universe wou... | null |
44j34u | why can't some, but not all, people with spinal cord injuries walk? | [
{
"answer": "The New Yorker did a pretty good article recently on spinal injuries [here.](_URL_0_)\n\nTL;DR: It depends where the injury occurs, generally the higher the injury, the more severe. That's why if you \"break your neck\" it's usually going to paralyze you, if not kill you outright. \n\nAdditionally,... | null |
4ncv90 | Is there any detailed map of Roman roads? I am interested in Roman roads in Croatia. | [
{
"answer": "Please allow me to recommend this... _URL_0_\n\n",
"provenance": null
},
{
"answer": "In addation to the awesome map /u/PaulAJK has, [this] (_URL_1_) map is zoomable. If you don't want ads for it, use [this one which is the same.] (_URL_2_)\n\n[This one also has a key.] (_URL_0_)",
... | null |
eyntiv | Is there a point at which eating will not stop you starving to death? | [
{
"answer": "Yes, particularly if you are being intentional and specific about the word \"eating\" The result can be what's called refeeding syndrome\n\n ( [_URL_0_](_URL_0_) ) where your body is unable to process or absorb nutrients properly. Since the kidneys shut down first, your ability to balance electroly... | null |
7187fg | Sources on how gunpowder/pike units functioned in 16th century and on, especially 30 Years' War, Tercios, Etc | [
{
"answer": "I can direct you to our own expert /u/itsalrightwithme and especially his [flaired user page](_URL_12_) which has plenty of resources.\n\nhe already answered several of question relating to your question like:\n > \n* [How did pike & shot formations work in battle?](_URL_4_)\n\n > * [Some aspects o... | null |
xi6a9 | How much water does a body absorb when showering? | [
{
"answer": "None. The epidermis is water proof. If it wasn't it'd allow ions to be leached from your body and bacteria in.",
"provenance": null
},
{
"answer": "Follow up question: Do you *lose* water from your body via sweat when you take a really hot shower?",
"provenance": null
},
{
"... | null |
2wu1en | why do local commercials appear to always have something go wrong with them while big corporation commercials don't? | [
{
"answer": "It takes money to make things look perfect. Most of the local businesses buy commercial air-time and the local broadcasting does the filming and editing. \n\nPrime example, my boss (local business owner) was offered a 15 second spot during the superbowl for around $5000. It would only be aired loca... | null |
4k77mt | why do you insist on seeing people suffer? dares, pranks, jackass movies.. why do we love seeing people do difficult and painful tasks? | [
{
"answer": "May not be the actual answer, just thought about it for a bit.\n\nWe don't like to see other people suffer. Would you go to a 3rd world country and laugh at every starving kid you see? Would you kick a physically-handicapped old man? Would you shoot someone and then laugh about it the next day?\n\n... | null |
g27971 | why is it recommended that we wait a little bit after turning something off to turn it back on? | [
{
"answer": "When you restart a pc it doesn't immediately turn back on again. The waiting is to let lingering electricity dissipate.",
"provenance": null
},
{
"answer": "Most electronics contain capacitors. Capacitors act like little buffers to even out current in a system. A bit like having a heade... | null |
24hiqy | how come people like bruce lee have such a small body, but are incredibly strong when athletes bigger than them are weaker even though they work out consistently? | [
{
"answer": "To begin with, there aren't many athletes like Bruce Lee! He was an outlier. ",
"provenance": null
},
{
"answer": "Muscle size and muscle strength have a bit of an odd relationship. Bodybuilders, for example, aren't terribly strong despite being literally living displays of muscle tone.... | null |
ynrqf | what motivation to hackers/pirates have to share pirated media with the masses? | [
{
"answer": "As someone who's pirated over 30 gigs of comic books, I've often wondered this myself. ",
"provenance": null
},
{
"answer": "They are smart enough to realize that if everyone leeches but no one seeds, there won't be anything there. \n \nSomeone who has a history of providing content... | null |
4ezwib | how do space shuttle engines work in space if there is no atmosphere to push against? | [
{
"answer": " > III. For every action there is an equal and opposite reaction.\n\nNewton really nailed this one. Grab a 10 pound bowling ball, a bag of flour, your child (no, I'm kidding), and hold it up against your chest. Now push it away from you as hard as you can. You should feel the ball moving away f... | null |
1kazwp | will cash ever become abolished in favor of debit/credit cards? | [
{
"answer": "Countries will have hard cash for the forseeable future. The black market runs on cash. Cash also works when the power is out / when there's no internet signal.",
"provenance": null
},
{
"answer": "I doubt it will ever go away completely. It's too convenient and reliable. It works whe... | null |
31pw2t | how do you best explain 4d to someone in a 3d world? | [
{
"answer": "Draw a line perpendicular to all three axis we currently use to view the world.",
"provenance": null
},
{
"answer": "We are 3D creatures. Our shadows are 2D.\n\nAn n-dimension casts an n-1 dimension shadow.\n\nThink about what could create a 3D shadow.",
"provenance": null
},
{
... | null |
c18ldh | why dont speakers make the characteristic intereference sound anymore when there is an incoming call? | [
{
"answer": "Ha yes, I remember that. You used to be able to hear that even before the phone rang.\n\nThe reason why it happened is a bit too complicated for me, but the reason why it doesn't happen anymore is that we don't (or barely) use 2G (GSM) networks anymore. These networks were on the 800-900 MHZ freque... | null |
9hq3r1 | What was the dating scene like for American women during WWII? | [
{
"answer": "For a large proportion of women, dating simply ... stopped. Their boyfriends or fiancés were overseas - instead of being taken out to movies or dinner, they wrote letters and waited for possible furloughs. Single college students usually had to give it up as well, since their campuses had almost no... | null |
40ruv9 | Where can I read more scholarly sources on Hawaiian "shark myths"? | [
{
"answer": "Try [here.](_URL_1_) That's a link to the UH School of Hawaiian Knowledge's Knowledge Well database.\n\nI haven't used this site before, but the University of Hawaii is really trying to cultivate their Hawaiian Studies programs, and that looks like it could potentially be a neat database. However, ... | null |
2zejt4 | We're constantly showered with radio waves. What prevents us from harnessing them and converting them into usable electrical energy? | [
{
"answer": "Simply put: ambient radio waves have very little energy compared to ambient visible light. Per photon, visible light has thousands to millions times more energy than radio waves. Also, the sun produces a lot more visible light than radio waves. If you want to harness ambient electromagnetic radiati... | null |
wmchx | Why do guns kill people so quickly (or are movies lying to me?) | [
{
"answer": "Movies are lying to you. As you suspected, gunshot wounds are very rarely instantly fatal. A shot to the abdomen or chest is often not even incapacitating for some time. \n\nAnecdotal, but relevant: my grandfather was shot through the throat by a high powered military rifle round, and wasn't at... | null |
2ncrlo | why do most of the tv series that use apple (or something else) as their primary technology change the os or make it look fake? | [
{
"answer": "It's similar to how they blur out logos on reality shows, they don't want to alienate potential advertisers. If they just show off an iPhone in their show, Samsung is not going to want to associate with them. Plus they're not being paid by Apple, so there's really no point to give someone free adve... | null |
3pwp1c | Is the universe older in different places due to time dilation? | [
{
"answer": "No, there's no time dilation between observers at a different place at the same cosmological time.\n\nWe do however observe time dilation with light from distant galaxies because the scale factor has changed in the time it took the light to travel to us. This time dilation manifests itself as a mea... | null |
62vzdj | How did Japan go about bringing electricity to its cities and towns? Did they hire westerners to teach them how to use it in order to make their own companies? | [
{
"answer": "After the Bakumatsu and the end of the Tokugawa Shogunate in 1867, the Meiji government came into power. From 1868 to 1912, was the Meiji Restoration, where the old emperor was given back power and Japan became the first Asian power to adopt the European model of government and military. From thi... | null |
brqi1n | why do remote controls use infrared light instead of other wavelengths? | [
{
"answer": "Very low wavelength bands are already occupied by radios and microwaves and have a lot of noise.\n\nVisible light is visible of course.\n\nUltraviolet is too energy intensive to generate, and you definitely don't want to be shooting x-rays around the living room.\n\nSo the near-IR it is.",
"pro... | null |
6m1r5v | why do some dead leaves tend to turn brown and others yellow/red/orange? what causes the difference in colours when they are dead if they were all green while on a tree? | [
{
"answer": "Chlorophyll is the reason they are green. When fall hits, the change in temperatures and decline in sun exposure causes leaves to break down the chlorophyll. Depending on the type of tree and chemical reactions you get different colors. \nThis is what I've learned from Google basically. \n\"Chlorop... | null |
8yn3nc | What was the role of slaves in early medieval Ireland? | [
{
"answer": "Slaves would have performed the most menial agricultural labour depending on their gender - a male slave called a *mug* would have tended to livestock (in the case of Saint Patrick, for instance) and chopped wood while a female slave called a *cumal* would have ground oats in a quern and kneaded do... | null |
63w0dz | how do farmers milk almonds? | [
{
"answer": "Almond milk is not actual milk. It is made by soaking almonds in water, then rinsing them and blending and grinding them well with water. Then the almond meal is filtered out and usually the remaining \"milk\" is sweetened slightly.\n\nIt is called milk because it is similar to dairy milk in appear... | null |
5dqphw | How did the Byzantines/Eastern Roman Empire lose the Battle of Yarmouk? | [
{
"answer": "An important thing to remember here is that these numbers are not accurate reflections of what actually happened. Modern historians of the Arab conquests are reluctant to believe the figures presented by the sources, the vast majority of which were written centuries later and were the results of a ... | null |
3077lp | How were alloys such as bronze (which require extremely high temperatures) made by neolithic civilizations? | [
{
"answer": "You're interested in the technological changes that marked the change from one culture to another? These kind of questions intrigue me too and also interested European archaeologists from the 19th C on.\n\nThe broad brush picture they paint is of successive waves of technological advances, spreadin... | null |
47gbjx | When did the Continental/US navy start to build Man o' Wars and Ships of the Lines? | [
{
"answer": "In 1776, when the Continental Congress authorized the construction of three ships of the line. However, only one ship was completed - the _America_ - and construction was delayed so much she was only in service by 1783, upon which she was transferred to the French Navy. She served only three years ... | null |
1loh4e | In ancient times, say for the Inca. What would happen if human sacrifice did not appease the Gods and relieve the drought? | [
{
"answer": "**I. In which I question the underlying assumptions and chronology of your question**\n\nFirst thing first, the Inca Empire had its heyday from the 15th to 16th Centuries CE, which is not \"ancient.\" Second, the nature of Inca theology was not one that necessarily included a direct transactional r... | null |
1f4ltx | how does the "tuner" on a radio work? | [
{
"answer": "There are two components in a radio that work kinda opposite of each other. They are the *inductor* and the *capacitor*. \n\nAn *inductor* is a coil of wire. When we pass electricity through a coil of wire, it stores some of that energy in a magnetic field. That's how electromagnets are made.\n\nA ... | null |
16gimn | To what extent did Celtic peoples along Europe's Atlantic coast share culture and trade before Roman conquest? | [
{
"answer": "Celtic language and culture came to Britain and Ireland a bit later than on the continent. In fact, it most likely spread through trade and political dominance, displacing languages that were probably related to Basque. \n\nThe Celts would have belonged to various smaller tribes, but all spoke a ve... | null |
1ev02s | what's going on with the irs right now? | [
{
"answer": "Some groups can apply for tax-exempt status if they are primarily involved in social welfare. Some political groups want to get in on this tax exemption, and not have to disclose donor names. It was found that when the words \"tea party\" or \"patriot\" were in the name of a group applying for tax ... | null |
201nng | Why exactly did the Soviet Union go to war with Finland? Why were they so ill prepared? | [
{
"answer": " > What did they seek to gain out of it? \n\nFinland had been part of the Russian Empire (as a sort of pseudo-autonomous Grand Duchy, whose Grand Duke just happened to be the Tsar) until 1917 and, when Russia descended into revolution and civil war, so did Finland, only there the reds lost.\n\n(Fu... | null |
18r5n6 | why do your emotions come in 'waves' after something very emotional occurs? | [
{
"answer": "most emotions come from chemicals in the brain such as dopamine, oxytocin, adrenalin, serotonin, etc. When your brain starts to release these chemicals, it doesn't happen all at once. It begins to secrete them as if opening a valve. The flow starts slow until you get enough of the chemicals and you... | null |
vtfmk | [South America] How did Paraguay rebuild its population after the War of the Triple Alliance | [
{
"answer": "Do you have a link to the article you refer to? I'd be curious to read it.",
"provenance": null
},
{
"answer": "Not an historian here, just a Brazilian that studied that on high school and did a bit of reading in wikipedia. About the third question:\nThe war had much to do with the Urug... | null |
2ygybw | Does the influence of gravity from objects with mass ever reach 0? | [
{
"answer": "It never reaches zero. The force of gravity is inversely proportional to the square of the distance, so it decays asymptotically to zero as you increase the distance (for example, if you double the distance, the force becomes 4 times smaller; if you increase it 100 times, the force becomes 10000 ti... | null |
6cdjhf | why do some people look "good" fat, and others look "bad" fat? | [
{
"answer": "Confidence goes a long way in this respect. If you feel less confident when you gain weight, you'll feel like you look less attractive. As for others, the ones that look good to you are likely not only confident but also dress for their body in a way that is flattering. Personal grooming goes a lon... | null |
1yfq36 | we often hear about first world and third world countries/problems ect. but why do we never hear about second world? | [
{
"answer": "This was an old term not used for poverty or whatever but in the cold war places like america and the uk where the first world russia ect the 2nd world and places that had nothing to do with it where the 3rd world which just happened to be all the poor places with no nukes",
"provenance": null
... | null |
4ram3z | Why didn't warships of the 18th century use explosive shells against each other? | [
{
"answer": "The overly glib answer to this is that they weren't invented yet, or at least not invented in a manner that would be useful. Although explosive shells date back to the 1300s, around the time of the invention of cannon, shells of the 18th c. were fused by an actual fuse (think of a cartoon bomb with... | null |
y5zbl | how do the companies behind linux distros such as ubuntu and opensuse make money if their os is free and open-source? | [
{
"answer": "They offer the OS for free but charge for some kind of services (that can be modifications or support and they know their \"free\" product the best).\n\nIf you don't need any support or modifications then it's easy to buy into. And when you need extra services you can buy it from them but at the sa... | null |
4wjjxo | why when someone records the cinema screen using a camera, the video becomes ugly and not the same as the screen? | [
{
"answer": "A few things. \n\n1) Most cameras record at 30fps, where as most films are 24fps. This leads to weird things happening due to the timing of the frames such as flashing and flickering. \n\n2) Cameras, especially cheap ones, struggle in low light. Also, movies are constantly changing between bright a... | null |
a7gpt4 | why do people open their own mouth when spoon-feeding a baby? | [
{
"answer": "To give the baby a visual cue of what to do and hope they mimic the movement. ",
"provenance": null
},
{
"answer": "Trying to model the behaviour. If the baby sees them opening their mouth, the baby might open their own mouth so they can be fed.",
"provenance": null
},
{
"an... | null |
1sv1bc | why can adults get diseases only by touching grabpoles on public transport while children's immune system profit from eating dirt/playing in dirt? | [
{
"answer": "Children do not benefit from eating dirt. Children are more exposed to germs and therefore slowly build up immunities to common viruses. Not diseases, by the way.\n\nAdults do not get diseases only by touching public transport poles. Adults are more segregated than children, who are in schools al... | null |
1iwj7l | how do you calculate the 20th percentile of a cumulative frequency? | [
{
"answer": "ELI5 isn't for walkthroughs. Try /r/learnmath or /r/cheatatmathhomework.\nThanks. removing.",
"provenance": null
},
{
"answer": null,
"provenance": [
{
"wikipedia_id": "45064451",
"title": "Cumulative frequency analysis",
"section": "",
"start... | null |
3g08t6 | what's the deal with movie theater shootings? | [
{
"answer": "Like any mass shooting, they get tons of Media attention, inspiring the next round of mentally unwell individuals to become copycats. Combine that with virtually non existent security in movie theaters, and you've got an easy target full of people.",
"provenance": null
},
{
"answer": nu... | null |
2ekquf | why is there so much abuse in the foster system? shouldn't there be more extensive background checks? | [
{
"answer": "I work in a related field. Honestly, there should be several changes. There aren't enough workers or enough of a budget to do enough. Also, who says that these abusers have done it in the past? A background check wouldn't help there.",
"provenance": null
},
{
"answer": "Contrary to popu... | null |
f606et | why is it that i’m some cases of people being stabbed/impaled, the removal of the item that did the stabbing/impaling (not the initial puncture itself) causes them to bleed out and die? | [
{
"answer": "Because the object basically acts like a plug when someone is impaled, as soon as you pull it out then the blood has nothing to even try and stop it from flowing freely out of the wound , that’s my guess",
"provenance": null
},
{
"answer": "If the object has punctured an artery (a blood... | null |
60fy5a | how can a single cpu core run multiple threads and how is that beneficial? | [
{
"answer": "Well, a single core can't directly run several threads. What happens is your operating system (windows) switches between these threads when it needs to, with only one ever active at a time. \n\nThe prime benefit is that it lets you do multiple things in time that otherwise would be wasted. For exam... | null |
461gal | why does the doubling your money strategy not work in gambling? | [
{
"answer": "The house pretty much always has the advantage. You also don't have infinite funds and losing streaks happen. You are basically guaranteed to eventually lose everything. ",
"provenance": null
},
{
"answer": "In theory it works, but in practice eventually you'll lose enough bets in a... | null |
2x2kw2 | How did the cicada's mating cycle come to be 17 years long? Wouldn't a cycle of only a few years be necessary to avoid lining up with predatory mating cycles? | [
{
"answer": "It's very beneficial to take a prime number as the length of your mating cycle. If you'd take 4 years for example, any predator that has a cycle of 1, 2 or 4 would eat a large part of the population. If you take a prime number like 7, then predators with a cycle of 2, 3, 4, 5, 6 will all miss you. ... | null |
cioo2l | how the us lost the ability/technology to land on the moon, after 50 years of industry advancement | [
{
"answer": "We haven't. In fact Nasa plans on putting a man on the moon in 2024. Planning missions like these takes a long time in advaced, because literally every contingency needs to be planned for. Not to mention we plan to use it as a test for a new rocket design. These things have to be built, people ne... | null |
2p1n28 | Why didnt Soviets force Finland to adopt a socialist government after WW2? And why did Finland never join the Warsaw Pact? | [
{
"answer": "Finland was never occupied by Soviet troops. They never got past a certain point. At that point in time in 1944, the Soviets were more interested in moving as fast as possible into Germany rather than trying to move deeper into Finland and possibly occupying it. When Finland sued for peace, both si... | null |
2aalj0 | if most youtube ads can be skipped after 5 seconds, why don't advertisers start making 5 second ads? | [
{
"answer": "It's incredibly hard to make an ad that actually works in five seconds - even if you manage to cram your logo, product, slogan and some positive remark into that, the average person won't remember it.\nBut lots of people just leave the ad running - not the majority, but enough to work better than f... | null |
2cxyj6 | why websites using cookies to better target your ads is considered such a bad thing. | [
{
"answer": "Because I don't want family visiting sites on my laptop and seeing penis pump ads on sites just because I clicked on an ad last night.\n\nEdit: er umm... not that I need one :(",
"provenance": null
},
{
"answer": null,
"provenance": [
{
"wikipedia_id": "9933471",
... | null |
b6zvtm | in computer architecture, what is the difference between core and a microarchitecture? | [
{
"answer": "A multi-core processor is a way to say that you have multiple independent processing unit on the same physical chip. Each is called a core and they will be identical in the chip for computers but in a cellphones the might have 4 energy efficient but slower cores and 4 faster that use more energy to... | null |
2s8v2n | how do astronomers know a black hole has the mass of 20 billion suns? | [
{
"answer": "A black hole is basically just a star that's collapsed in on itself, becoming very, very dense. Our Sun has a lot of gravity because it's so massive, but the only stars that can become black holes are hundreds of times bigger than our sun. So every black hole that's born has a similar mass to the... | null |
24hj5w | gas stations often have signs on the pump to turn off your phone and pager while using the pump. i doubt that anyone does this. what's the concern and is it a valid one? | [
{
"answer": "The concern is about the possibility of an electrical spark igniting the fumes of fuel. The source comes from an investigation of a fire at a gas station where they could not determine a cause many years ago. One difference was the car owner had a cell phone, (relatively new at the time. Hardly any... | null |
5ja2ym | what do all the parts of a url mean? | [
{
"answer": "The first bit before the colon (http, https etc) refers to the protocol in use. Http is the only common one but you can use others like ftp:// - which will use file transfer protocol. The next bit after the // is the address of the website - _URL_0_. After than, comes the file/script you are loadin... | null |
4fm4jr | how do some vehicles drive nearly submerged without stalling or breaking down? | [
{
"answer": "This is much easier with a diesel engine, particularly older ones which don't have masses of electronics. They're nearly all mechanical and don't much care if they're under water.\n\nMore modern diesels have to have more attention paid to waterproofing connectors and sensors and things, but provide... | null |
2tjpis | how do wills get invalidated by a court? | [
{
"answer": " > How can a court decide whether to honor or invalidate a will?\n\nOne way that a will can be invalidated is if it's deemed to be incomplete. For instance, a will that was first drafted 30 years ago, and doesn't mention children who are 25 years old, would be invalidated, because it's assumed tha... | null |
323oxs | what is it about riding in a car that makes babies fall asleep? | [
{
"answer": "Vibration, warmth, hum of the engine all come into play. I wish I could find a link to a study, but if the cars are moving at a relatively good speed, children can't focus on objects outside of the vehicle. Without anything to pay attention to they lose interest and their bodies choose rest instead... | null |
3y103f | Do black holes have an escape velocity? | [
{
"answer": " > Or is this a nonsensical question? \n\nBingo. I know you mentioned \"what if + time travel,\" but entertaining these miss the point of physics because they disregard physics entirely.\n\nIn any case, as long as you kept outside the horizon you would have an escape velocity. Once inside, well sh... | null |
r8wcw | Health differences between animal protein and plant protein? | [
{
"answer": "Animal protein is a complete protein. It contains all nine essential amino acids that our bodies need. Vegetable proteins do not generally contain all nine amino acids. However, by combining foods you can make a complete protein. Rice and beans are an example.\n",
"provenance": null
},
{
... | null |
6wtnqa | why are different parts of the world more prone to extreme weather? | [
{
"answer": "There's a few factors that are happening. The big ones are:\n\n* the middle of the planet is warm\n* the poles of the planet are cold\n* warm air expands (pushing other air) and rises\n* warm water evaporates\n* cold water condenses and falls\n* the rotation of the planet produces some pretty predi... | null |
1q8nwg | if colds are caused by viruses and bacteria, why do i often feel like i get a cold from just staying at low temperatures without proper clothing? | [
{
"answer": "They're not caused by any bacteria. They're both caused by viruses.\n\nAnd to answer the question, coincidence or you're just remembering the times the two coincided. ",
"provenance": null
},
{
"answer": "When the weather is cold, people spend more time inside. The close proximity of ... | null |
4y8uzo | how do services such as 'bongo' in the uk know any details about a person, and are they even real? | [
{
"answer": "From their FAQ:\n\n > HOW DOES BONGO WORK?\n\n > BONGO works thanks to a number of intelligent human researchers and a very sophisticated software application with a huge database.\n\nSo officially, they say it's a mixture of human researchers and a software application. Presumably they are collect... | null |
e7guez | why do all legitimate streams run almost half a minute behind their television counterparts? | [
{
"answer": "i'll give you a placeholder answer that you can hold onto until someone who's worked with this technology at a lower level can speak on it.\n\n\n\nThere is a lot of preprocessing that goes on with video, sending it too. You don't get sent raw video data of every pixel at every frame - which is why ... | null |
ej72gj | why you’re told to wait 30 seconds when unplugging a modem or dvr. | [
{
"answer": "When you unplug it, there is still electricity in the device. Think of it like a sink, and electricity is water. Pull the plug and let it drain.",
"provenance": null
},
{
"answer": "Electric circuits have parts called capacitors which can hold on to electric charge for a bit.\n\nIn orde... | null |
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