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Tuesday, April 3, 2018

How is the fatigue life of an airplane wing flexing during turbulence determined? How do they keep track of it?

How is the fatigue life of an airplane wing flexing during turbulence determined? How do they keep track of it?


How is the fatigue life of an airplane wing flexing during turbulence determined? How do they keep track of it?

Posted: 02 Apr 2018 03:52 PM PDT

How can a bolt from a crossbow have a higher penetration power but less range than an arrow from a bow?

Posted: 03 Apr 2018 12:59 AM PDT

Why are there as many electrons as protons in the universe?

Posted: 03 Apr 2018 02:06 AM PDT

Can any animals ACTUALLY smell fear?

Posted: 03 Apr 2018 05:31 AM PDT

I've heard it about numerous animals, but can are there any species with the ability to detect fear through scent?

submitted by /u/TheClayrooAtWork
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Does irradiation of food for safety purposes affect nutritional content?

Posted: 03 Apr 2018 07:08 AM PDT

[Physics] Why neutrons are uncharged? Why it's important?What happens if it does not exist?

Posted: 03 Apr 2018 04:57 AM PDT

Hydrogens don't have neutrons why other elements have it?what happens if we remove neutrons from other elements is it possible to do that? (Sorry for my grammar mistakes) :)

submitted by /u/7Royale
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Why do rockets only use chemical reaction (fuel, oxidizer, cryogenics, etc.) boosters? Why not a chemical/ion/nuclear combo? Size a big factor?

Posted: 02 Apr 2018 10:21 PM PDT

My thinking would be chemical boosters to exit earths atmosphere, and a nuclear/ion booster for deep space travel.

submitted by /u/FriendlyFonzi
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Can Astronomers actually see other galaxies rotating, other stars moving, and other such events in "real-time" or does space appear to stand still?

Posted: 02 Apr 2018 09:59 PM PDT

I know that we are able to detect planets by measuring the light from stars when a planet passes in front of it. Though that is perhaps the only "real-time" event that I know of that we observe.

What sort of activity in the cosmos can we watch in real-time? For example, since the Sombrero Galaxy has been found, has it rotated enough to reveal more of it's structure or appear exactly the same after all these years?

Sorry if this seems like a painfully stupid question.

submitted by /u/4Nia
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What makes a chemical dangerous to smell?

Posted: 02 Apr 2018 04:55 PM PDT

Is the empty space near the Sun (say, closer than Mercury) hot or cold?

Posted: 02 Apr 2018 02:41 PM PDT

I know that once you leave the atmosphere things get mad cold out there, and heat needs some kind of medium to propagate through(?). But I also know that the Sun is really, extremely hot, and the heat on earth I presume has to get here somehow. If you were floating in space near the sun, would you burn to a crisp or freeze (after you suffocate, obvs)? If it's hot, what is the heat propagating through?

submitted by /u/Ferociousaurus
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What, atomically, happens when electricity arcs and produces light?

Posted: 02 Apr 2018 03:48 PM PDT

I understand that when electrons are forced to change energy state in an atom this produces light of specific energy levels, is it something similar, or have I got that bit wrong as well?

submitted by /u/King_Bonio
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How aware are humans of our surroundings when we sleep?

Posted: 02 Apr 2018 08:02 AM PDT

I ask this because I spent the last few nights sleeping in a hotel room, and for whatever reason- I woke up every few hours. When I'm sleeping in my own bed, I rarely wake up until the alarm sounds.

Another thing that I noticed is that if I fall asleep in my bed, I can roll around and end up in weird positions or on the other side of the bed, yet if I fall asleep on a bench or shallow couch, I wont roll off and fall on the floor.

These occurrences lead me to believe that we must have some senses active while we're sleeping that remains responsible for sensing our surroundings.

submitted by /u/cupbell2000
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Why does freezing work for embryos but not adults?

Posted: 02 Apr 2018 10:29 AM PDT

How do Economists Calculate how much Currency to Mint?

Posted: 02 Apr 2018 08:36 AM PDT

For given countries, are there 'go to' formulas used for Economists to calculate how much new money the government should be minting at a given moment?

What kind of variables does it operate on, and if there are more than one, what are the pros and cons of each?

Seems like a very difficult problem that must have been solved to some degree by someone at some point.

submitted by /u/lionhart280
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Since they just claimed to find a star that is 9 billion light years away, would this change how old and big the universe is?

Posted: 02 Apr 2018 02:28 PM PDT

As I understand it, the universe is as big as however far it is to the furthest we can detect light from, multiplied by 2 to give us the diameter. Link: http://go.newsfusion.com/nasa-news/item/5561790

submitted by /u/HumanoidParanoid
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Why do storms on our solar systems outer planets last so long?

Posted: 02 Apr 2018 01:08 PM PDT

Title. Earth's toughest storms seem to only last a few weeks. But storms on the outer most planets have storms which have lasted for years or decades. What is so different about Earth?

submitted by /u/Zebrasaurus-Rex
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If a solar panel isn't connected to a power grid, what happens to the electricity generated?

Posted: 02 Apr 2018 10:42 PM PDT

I'm currently aboard train with electric wall sockets for every seat. Is it possible to use so much electricity that the train is slowed down?

Posted: 02 Apr 2018 10:53 AM PDT

The train is 8 carriages long with an electric locomotive at the front end. Each carriage looks to have about sixty seats each, each seat has with 2 standard European 240V sockets (two sockets under each pair of seats, two in front). Doing the maths, that works out to 1920 sockets.

While I haven't tried to overload the capacity, I forgot to bring any high-wattage appliances for my journey, and so did the rest of the passengers.

So, is it possible to make the conductors and staff at least notice something if every single socket is in use? Just a thought.

submitted by /u/ral008
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Why does injury recovery focus heavily on reducing inflammation?

Posted: 02 Apr 2018 09:35 AM PDT

Rest, elevate, ice, wrap, take NSAIDs.

How does it make me heal quicker to reduce inflammation?

submitted by /u/gdubrocks
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If the entire moon exploded would the proximity to earth allow for sound to be transmitted back to earth on a global scale and be heard in ways similar to that of a bomb explosion?

Posted: 02 Apr 2018 07:57 PM PDT

How do contraceptive pills work when taken consecutively?

Posted: 02 Apr 2018 12:23 PM PDT

As I was studying biology today and exactly the moment I was looking at how contraceptive pills work, my dad looked over and started asking me to explain it...then I realized I have the basic knowledge of how contraceptive pills work but haven't grasped the full, intricated details. At least not how they work with the hormones levels. Then, my mother starting asking about taking the pills consecutively, because she notices I sometimes take them two packs after each other. I did not have an answer to it, hence I am wondering the exact procedure when I take them back to back without a stop.

submitted by /u/Daisuki_29
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Monday, April 2, 2018

What’s the difference between men’s and women’s multivitamins?

What’s the difference between men’s and women’s multivitamins?


What’s the difference between men’s and women’s multivitamins?

Posted: 01 Apr 2018 10:27 PM PDT

When a person observes light at the limits of the visible spectrum, what does the transition to UV or IR look like?

Posted: 01 Apr 2018 10:06 PM PDT

Does it gradually fade away or is there a point where it suddenly goes black?

submitted by /u/angryco1
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How many metric tonnes of plants/fossils were necessary to generate such immense amounts of oil?

Posted: 02 Apr 2018 04:07 AM PDT

Is there any way to prove that all points on the number line correspond to a real number?

Posted: 01 Apr 2018 09:57 PM PDT

And vice versa (that all real numbers have a unique spot on the number line)? If so, what is it?

I've noticed that this is something I've been assuming for a while. I was wondering if this is just a convenient shorthand or if there is a rigorous connection.

submitted by /u/ACuteMonkeysUncle
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Which is brighter, a full moon from earth or a full earth from the moon?

Posted: 01 Apr 2018 10:26 PM PDT

Are chewable vitamins more easily absorbed by the body than “pill” vitamins?

Posted: 02 Apr 2018 05:01 AM PDT

My friend told me that chewable are more easily absorbed by the body. Is that true?

submitted by /u/BlargAttack
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How do robins find worms underground? Are they able to locate food more accurately than simply guessing and digging?

Posted: 02 Apr 2018 06:03 AM PDT

How does being born blind or deaf influence the way you think?

Posted: 02 Apr 2018 05:52 AM PDT

Can immunization be passed on?

Posted: 01 Apr 2018 09:06 PM PDT

Can some one tell me if I made someone immune to a virus using CRISPR could they pass on that immunization?

submitted by /u/notbored1
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Do all stars have the same photospheric composition?

Posted: 01 Apr 2018 07:33 PM PDT

I googled this question and only received vaguely related articles and blog posts. I would assume the photospheric composition of a star changes whit the different stages of a stars life cycle (O to M classes) but I would like to know for sure rather than accept false information.

submitted by /u/Magi-Koopa
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How did fish appear in Endorheic basins such as the Caspian Sea?

Posted: 01 Apr 2018 11:17 PM PDT

Why does a note on a guitar sound different on a piano (and every other instrument)?

Posted: 02 Apr 2018 02:44 AM PDT

Why does a spaceship burn on return and not on the way out of the atmosphere?

Posted: 02 Apr 2018 02:23 AM PDT

why do we supply IV fluid or any other pain relieving drug through blood stream not make the patient just drink it?

Posted: 02 Apr 2018 05:59 AM PDT

Humans and countless other species use mouths to both eat and make sounds. Are there animals out there that produce sounds from a part of their body that isn't where they also consume?

Posted: 01 Apr 2018 10:54 PM PDT

Do we have satellites around other celestial bodies?

Posted: 01 Apr 2018 11:44 AM PDT

I've always wondered. We do fly-bys with probes, but why not just park an imaging satalite above, say, Jupiter so we can monitor it and its moons for years? Or do we already have something like that?

submitted by /u/TrueRadicalDreamer
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Why do the beeps from Sputnik sound like they are echoey? Is this bouncing of the radio signals or something about how the sound was generated?

Posted: 01 Apr 2018 11:03 AM PDT

The sound, for reference: https://youtu.be/lfnfNe31fmY

submitted by /u/dyyys1
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Which would burn more calories by: running a mile, walking a mile, or are they the same?

Posted: 01 Apr 2018 01:14 PM PDT

I think this may boil down to a biomechanics problem and is probably affected by running and walking form. If that's the case, you can assume the most energy-efficient walking and running form.

submitted by /u/Shake_That_Acetone
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How does the size of a proton change under different conditions?

Posted: 01 Apr 2018 03:14 PM PDT

Within different sizes of atomic nuclei what governs changes in the size of the proton? What conjecture is there? What do we know? And how does this affect the density of atomic nuclei?

If any astrophysics people know anything about say matter in extreme conditions and it's affect on size that would be interesting to hear as well.

submitted by /u/A_Mathematician
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What is the difference between freeze-out and decoupling?

Posted: 01 Apr 2018 11:47 PM PDT

I've been trying to figure out what the difference between freeze-out and decoupling is with the help of books and google, however I've not been able to come up with anything useful - most everyone equates the terms but that begs the question why there exist such different terms.

As I understand it, decoupling means that the particle class we speak of is no longer in thermal equilibrium with it's surroundings. Thus the universe become transparent and they propagate freely from then on - not interacting with the rest.

Freeze out means that the particle abundance becomes constant - i.e. there is no more interaction with the rest and equilibrium is left behind.

Are my understandings of freeze-out and decoupling right? And what then is the difference between the two?

submitted by /u/writerstears
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What does it mean that "the electromagnetic force is carried by photons"?

Posted: 01 Apr 2018 09:18 AM PDT

So I kind of sort of understand what a force carrier is, and I know that photons are the force carrier for the electromagnetic force. But what does that mean, exactly? When I put two magnets together, they don't emit light or anything, and particles can't pull things together, only push them apart. So what role do photons play in this interaction?

And I'd assume that photons are also to blame when it comes to positively charged particles attracting negatively charged particles, but how does that work? Again, particles fired toward another particle should only be able to push them apart, right? So how exactly does the exchange of photons keep charged particles together?

And lastly, what about when magnet poles or like-charged particles get close together? I'd assume in this case, photons exchanged between the two objects would push them apart, but why don't we see any visible light when this occurs?

submitted by /u/Popopopper123
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Does the moon/sun's gravitational pull affect how high I can jump height on earth?

Posted: 01 Apr 2018 01:15 PM PDT

The moon and sun have effects on gravity on earth, which can be seen with the tides, human physiology, and more. My question is if the pull of the moon and sun have enough of an effect on the gravitational acceleration here on earth that I could be able to jump slightly higher when the moon/sun are overhead than when the moon/sun are underneath us?

Thanks, rainbows82

submitted by /u/rainbows82
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Do animals have social and behaviour-affecting substances, like alcohol is for humans?

Posted: 01 Apr 2018 01:51 PM PDT

Sunday, April 1, 2018

How did they beam back live images from the moon before the invention of the CCD or digital sensor?? What device turned the image into radio waves?

How did they beam back live images from the moon before the invention of the CCD or digital sensor?? What device turned the image into radio waves?


How did they beam back live images from the moon before the invention of the CCD or digital sensor?? What device turned the image into radio waves?

Posted: 01 Apr 2018 02:49 AM PDT

How does light from research submarines affect deep sea ecosystems?

Posted: 01 Apr 2018 03:32 AM PDT

I'm just watching some Planet Earth II and I noticed that the submarines are using what seems to be visible light to observe life at the bottom of the ocean near Antarctica. How does this light interact with these deep sea ecosystems?

submitted by /u/EveryDayIsLikeMonday
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What causes this reverse funnel effect from the expulsion gases of a rocket launch?

Posted: 01 Apr 2018 02:54 AM PDT

In a recent SpaceX launch, I noticed a very clear "reverse funnel" effect coming from the thrust(?)/expulsion gases(?) at around 23:40 in this video.

It happens just after max Q (which I only understand to be "maximum dynamic pressure"), though I'm not sure if that has something to do with the effect or if it just becomes more visible at that point. It seems to disappear at around 24:15, but it might just be offscreen.

Sort-of follow up question: is there something that changes in the system that does and/or would cause the effect to stop?

submitted by /u/internet_eq_epic
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Can inconel be made with tungsten in it?

Posted: 01 Apr 2018 01:27 AM PDT

On the Wikipedia page for inconel, there's a list of the most common alloys of it and what percentages of what types of metal go into making each specific alloy. I noticed that none of them involve tungsten which was surprising to me because inconel is used commonly in such high heat and strength applications.

Is there something I don't know about metallurgy that prevents tungsten from being a part of any inconel mix?

submitted by /u/Elbynerual
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Why do ceramic objects make a lot of noise for their impact, relative to many other materials?

Posted: 31 Mar 2018 06:13 PM PDT

I read this story and it got me thinking about that. About how a toilet tank lid nearly caused permanent hearing damage for dropping a "mere" 8 inches. I know this myself from accidentally dropping the edge of a plate, just a few inches. The plates don't break but they are damn loud. What makes these ceramics so loud on impact?

submitted by /u/ccricers
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Is it possible to "carbonate" liquids with other gasses?

Posted: 31 Mar 2018 04:16 PM PDT

What is special about carbon dioxide? can we use other gasses to "carbonate" a liquid instead? If so why c02. If not why can't we.

submitted by /u/abk03
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Why is it that alloying one metal (copper) with another metal that is softer (tin) creates a product (bronze) that is harder than copper, not softer? Is there something about the process of alloying itself that creates hardness?

Posted: 01 Apr 2018 04:27 AM PDT

I've taken up metalworking lately, I started cold working copper, moved up to casting, alloying and hot working copper, brass and bronze and about a month ago I started learning how to forge iron. I've learned a lot of metallurgical science, especially as a result of learning about heat treating, the mollecular stuff that causes copper to become softer when annealed, or steel to become harder when heated to the critical point and then rapidly cooled by quenching. One thing that I don't know, but I am curious, is why is it that alloying metals creates harder material regardless of the individual components of the alloy — that might not make sense in the way that I've expressed it so here's an example of what I mean, Bronze is an alloy of approximately 85-88% copper and 12-15% tin, and it is significantly harder than copper, however tin is very soft, soft enough that a tin ingot can be deformed by squeezing it with bare hands, similarly brass is 84-86% copper and 14-16-% with 0.5-1% lead in older pieces, it is also harder than copper (but softer than bronze) even though zinc and lead are very soft and much softer than copper — why is it that adding a softer metal to copper makes it harder as opposed to soft? To me that doesn't make any sort of logical sense, since in simple terms if I were to take a cup of water that was 30% sugar (softness) and add another half-cup of water that was 65% sugar, it would have a higher sugar content than it's individual parts and thus be more sweet than the cup that we started with, not less.

submitted by /u/Louisianais
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Why is there layers in the atmosphere is it's all the same gas, like how do they decide where the layer stops and the next starts?

Posted: 31 Mar 2018 04:31 PM PDT

Is it theoretically possible to create a cure for all types of cancer? Or when people say "a cure for cancer," they just mean finding more ways to treat specific types of cancer

Posted: 31 Mar 2018 05:40 PM PDT

What percentage of the water you drink turns to urine, and what percentage goes elsewhere?

Posted: 01 Apr 2018 06:14 AM PDT

What allows our smartphones to easily register a human touch as input, but negate that of an inanimate object, like a pen?

Posted: 31 Mar 2018 05:47 PM PDT

I heard that some of the first radios used crystals to 'receive' radio waves. How does this work, and are newer radios operating along the same principle?

Posted: 31 Mar 2018 06:25 PM PDT

Does each radio need a crystal in order to function, or do newer radios function in a different manner? thanks

submitted by /u/Jay_B_
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Why is multicollinearity a problem?

Posted: 31 Mar 2018 07:55 PM PDT

Recently in classes I've been learning about multicollinearity, and from what I'm understanding it's when independent variables in a regression have a high correlation with one another. Why would this be a problem, and could you maybe give a real life scenario example showing how this affects the data? Thank you!

submitted by /u/integralfallacy
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How doesn't entropy break the law of conservation of energy?

Posted: 31 Mar 2018 05:54 PM PDT

Hi guys, I currently read somewhere that the law of conservation of energy only works in processes that are time-symmetrical, meaning that we can't tell whether we are observing the said processes in reverse or not; that's why the density of dark energy is constant as space expands and therefore we have more dark energy as time moves forward.

Now, as we know, the total entropy of the universe is supposed to increase over time. Therefore the universe should have more and more entropy as time passes on. Plus the fact that the law of conservation of energy should hold for isolated systems.

Finally, Here's my question: Can we consider the entire universe as an isolated system? (I mean, what else is there to affect it?) And if so, what keeps this increasing entropy of the universe from breaking the law of conservation of energy? (Cause, you know, otherwise thermodynamics would be paradoxical, right?)

submitted by /u/ILoveSheikyBubba
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Do Aquatic Animals Suffer from Infectious Diseases?

Posted: 31 Mar 2018 03:32 PM PDT

Is there a upper bound on how fast planes can travel safely over long distances?

Posted: 31 Mar 2018 06:15 PM PDT

If let's say the government wanted build the fastest plane possible, what is the physical limit to how fast a plane can travel over distances of thousands of miles before it becomes too unstable?

submitted by /u/JirenTheGay
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Why does temperature in the thermosphere increase with altitude?

Posted: 31 Mar 2018 07:54 PM PDT

It there another sphere above this? Because the temperature of space is almost zero (K) But the temperature of the highest sphere is increasing?
I was looking at temperature against altitude graphs. Thank you

submitted by /u/sedg12
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Why do I feel my phone go off in my pocket when it is neither going off nor in my pocket?

Posted: 31 Mar 2018 11:13 AM PDT

In terms of half life, why do certain particles of an element decay while others don't? Why don't all of them decay?

Posted: 31 Mar 2018 10:53 AM PDT

For example, for Carbon-14, why do certain particles of that isotope decay and others don't? Aren't they the same? And where do the particles that do decay go?

submitted by /u/ItsYoBoiGuzma
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Does looking through the atmosphere refract the image we see similar to looking through the surface of water?

Posted: 31 Mar 2018 10:53 AM PDT

I don't think so, otherwise a telescope would be a terrible astral positioning system.

submitted by /u/Hippiedownsouth16
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How developed are the chicks inside eggs when they're laid?

Posted: 31 Mar 2018 02:06 PM PDT

What determines how much dark matter a celestial body has?

Posted: 31 Mar 2018 04:18 PM PDT

I have recently been reading a lot about dark matter and I have been wondering how do scientists determine how much dark matter a celestial body contains. I know that scientist know that dark matter exists because some galaxies spin faster than their gravity holds them together, so there has to be something invisible that is providing an extra force that keeps it together. However, I recently came across this article https://www.independent.co.uk/news/science/distant-galaxy-dark-matter-universe-understanding-theories-wrong-space-yale-a8277951.html that states that there is a galaxy with no dark matter. How are scientists able to calculate whether galaxy contains dark matter? Also, how are they able to avoid the distortion of light that could give them inaccurate results?

submitted by /u/toomysxs
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How were cranial nerve functions determined?

Posted: 31 Mar 2018 04:12 PM PDT

Is this based solely off experiments with rats and case studies from people with very specific cranial nerve injuries? Where do textbooks draw this information from?

submitted by /u/kokiloco
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