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Sunday, October 15, 2017

Why is it that when you turn on a fluorescent light, it flickers before becoming a stable light source?

Why is it that when you turn on a fluorescent light, it flickers before becoming a stable light source?


Why is it that when you turn on a fluorescent light, it flickers before becoming a stable light source?

Posted: 14 Oct 2017 09:01 PM PDT

Nuclear power plants, how long could they run by themselves after an epidemic that cripples humanity?

Posted: 15 Oct 2017 07:42 AM PDT

We always see these apocalypse shows where the small groups of survivors are trying to carve out a little piece of the earth to survive on, but what about those nuclear power plants that are now without their maintenance crews? How long could they last without people manning them?

submitted by /u/Marius423
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Why is plasma considered the fourth state of matter when it is just gas that has been ionised?

Posted: 15 Oct 2017 07:31 AM PDT

I mean, what makes it a different type of matter from gas. Also, is plasma the same thing that you get when you atomise an element and then make it undergo either electron affinities or removal of electrons?

submitted by /u/CarbonoAtom
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How is our liver able to regenerate itself, when our other organs cannot?

Posted: 14 Oct 2017 07:33 PM PDT

Like a Faraday cage for electricity, can we build something for magnetism? If not, why?

Posted: 15 Oct 2017 07:39 AM PDT

Idea is to prevent a magnetic field from affecting an object when placed inside this "magnetic cage".

submitted by /u/SingsWithDucks
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[Biology] In molecular biology, is there an alternative way of separating DNA fragments other than gel electrophoresis?

Posted: 15 Oct 2017 07:24 AM PDT

Cloning DNA in plasmids would be much faster if we didn´t have to use this archaic technology.

IMHO, gel electrophoresis, western blots, manual hemocytometer cell counts (and other archaic lab techniques) only survive in the lab because of the high amount of cheap labor (postdocs) available ....but that´s another discussion....

submitted by /u/Jatobaspix
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Cause of matter's solid nature - Coulomb force or degeneracy pressure?

Posted: 15 Oct 2017 07:18 AM PDT

I was taught in undergrad that it is the coulomb force that gives matter its solid nature. When you bring macroscopic objects with mass real close together charges repel each other. Charges repelling each other are what happen when we "touch" objects together.

But I have seen some claim that it is in fact degeneracy pressure that causes mass to be solid. (I have seen it cited on wikipedia, but can't find it now.) I guess this implies there simply isn't any quantum state that allows the two objects to interleave with each other. The exclusion principle excludes this.

I'm confused by this claim because I know that degenerate matter is a "thing", that is - it is distinguished from normal matter.

So my first question is in the post title - The solid nature of matter. Does that come from coulomb force or degeneracy?

My follow up question - It seems like it may be degeneracy. In this case what distinguishes degenerate matter from regular matter?

submitted by /u/Semiresistor
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How far back, and to what degree of accuracy, can models of the continents of the earth be run?

Posted: 15 Oct 2017 07:00 AM PDT

How far back could we 'run the reel' so to speak on how the continents were arranged and what the Earth's surface would have looked like? Are there any events that could take place(naturally) that could effect our predictions, for example a massive natural disaster that altered to course or changed the direction a tectonic plate was moving.

submitted by /u/BlueDreamWidow
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When I’m underwater wearing my swimming goggles, they improve my eyesight as if they were glasses. They don’t do this when I’m above water. Why does this happen?

Posted: 14 Oct 2017 10:43 AM PDT

I am nearsighted, so when I take my glasses off and put on my swimming goggles above water the world, predictably, becomes blurry. But under the water the goggles act almost like my glasses, and I'm curious why they do this.

I think it has something to do with the refractive index of water/the goggles but I'm not really sure. Thanks!

submitted by /u/XenlaMM9
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Why can we not hear what our actual voice sounds like?

Posted: 14 Oct 2017 03:35 PM PDT

How does frozen food ever go bad?

Posted: 14 Oct 2017 06:08 PM PDT

What happened to make LEDs so cheap recently?

Posted: 14 Oct 2017 08:49 PM PDT

Was there a particular advancement?

submitted by /u/hdfvbjyd
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If humans can harvest the tides for energy, and tides created from the gravitational push and pull of the moon, but gravity is not inherently energy, then where does the extra energy come from?

Posted: 14 Oct 2017 12:49 PM PDT

In other words, how is kinetic energy created from the gravitational interactions of two objects? Is this not where the energy is actually coming from? Article for reference

submitted by /u/JaxisBack
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How are old nukes disposed of?

Posted: 14 Oct 2017 07:50 PM PDT

If temperature is a measurement of the vibration of molecules, then how does the vacuum of space have a temperature?

Posted: 14 Oct 2017 10:57 AM PDT

Is it logically possible for humans not to have had a mitochondrial Eve?

Posted: 14 Oct 2017 02:28 PM PDT

Is a mitochondrial eve a logical necessity for humans given how mitochondria work in the context of human (or mamalial?) (or any) evolution?

submitted by /u/I_love_swiss_cheese
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As photons have momentum, is light from the sun slowly pushing all the planets away?

Posted: 14 Oct 2017 12:31 PM PDT

How is heavy water (deuterium oxide) used when making a nuclear weapon and why ?

Posted: 15 Oct 2017 12:46 AM PDT

Why does encrypting data take much longer than decrypting, if they're both inverse functions of each other?

Posted: 14 Oct 2017 06:19 PM PDT

For example, it took me around 10-11 hours to fully encrypt my 1TB drive, but it only takes milliseconds to access that data once the password is provided.

submitted by /u/krabbypattycar
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Why colonize Mars before the Moon?

Posted: 14 Oct 2017 08:22 PM PDT

Just a few thoughts I have had for a while. I've been watching and reading a lot of content on human colonization and the majority of the time it focuses on Mars. Even in the news nowadays it all talks about Mars colonization but what about the Moon?

I am no where near a specialist in this field at all but this is what I think. The Moon is closer to the Earth than any other celestial body, it has microgravity, very very very thin atmosphere.

To me it would just make more sense to colonize the moon first. Or at least have some type of port to make bigger ships since it will be easier due to the microgravity. Again it's closer to proximity to the Earth so we can shuttle the needed resources back and forth, not to mention we can actually test our capabilities to colonize another body before we put all chips into such a far target.

I understand Mars is the target of many peoples dreams but it just seems safer to do it one step at a time. Again I know humans are explorers, risk takers and the bunch but the Moon first just seems as a better step forward in terms of colonization.

Just a few thoughts here, I'd like to hear other thoughts on the subject.

submitted by /u/Marz_Tech
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Why does a little salt make ice in a cooler lower its temperature and even refreeze slightly, rather than just melt?

Posted: 14 Oct 2017 11:36 AM PDT

Learned this trick from a cook when our fridge died. We filled tubs with ice and sprinkled some salt on the top.

Not only did the ambient temperature of the inside of the fridge drop, but there was even ice reforming at the top, despite salt lowering the freezing point.

He tried to explain, but I was hoping for a more succinct and eloquent explanation. He said it had something to do with the salt being a heat sink.

submitted by /u/Djinnwrath
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[Physics] Do I gain mass when i am higher up?

Posted: 14 Oct 2017 11:36 AM PDT

I of course remember learning that you gain potential energy as you rise in the air, equivalent to E=mgh. But since E=mc2, would you gain the slightest bit of mass by at the same time? Follow up question if yes, how would that mass be stored? Is it just stored as energy?

submitted by /u/reeper147
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Saturday, October 14, 2017

Is there an optimal angle when dragging an object across the ground?

Is there an optimal angle when dragging an object across the ground?


Is there an optimal angle when dragging an object across the ground?

Posted: 13 Oct 2017 11:48 AM PDT

I watched an oxen pull competition last weekend and a conversation surrounding efficiency came up. The oxen (less than 2900lbs) were dragging a 1000lbs (steel) sled with 6000lbs of weight added to it across dirt. The rope connecting the two was somewhere between a 30-45 degrees incline. What is the most efficient way to drag this sled? A rope with no incline or is the upward force to reduce frictional force more efficient?

submitted by /u/mmiels
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How is quantum tunneling limited by speed of light?

Posted: 14 Oct 2017 01:36 AM PDT

My understanding is that a particle "exists" in the entire universe at varying probabilities, and can be measured at literally any point.

Instead of a very short distance, let's say a particle is going to tunnel one light second away. Does it take one second? Does it happen instantly? Is there really a frame of reference that shows it arriving before it's left?

submitted by /u/Daegs
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Over time do nuclear warheads become less powerful?

Posted: 14 Oct 2017 06:08 AM PDT

Can sound pass through the star when a supernova explodes?

Posted: 14 Oct 2017 04:50 AM PDT

Sound needs a medium, so there's no sound in space. However, I was wondering if sound could pass through the immensely dense star while it explodes.

submitted by /u/EatPussayNow69
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How does a species evolve to have a different number of chromosomes? Wouldn't the first individual with that mutation be unable to mate with any other individuals, and so the mutation would instantly die off?

Posted: 13 Oct 2017 05:57 PM PDT

Did the Great Wall of China affect the environment around it when it was built?

Posted: 13 Oct 2017 01:47 PM PDT

Could the large hadron collider accelerate a Bucky ball?

Posted: 13 Oct 2017 07:54 AM PDT

How does a group, such as NASA, even begin to set a rocket in the right direction?

Posted: 13 Oct 2017 03:35 PM PDT

It never ceases to astonish me how rockets, being so small relative to planets, can be targeted with almost dead accuracy in space to reach places like Pluto. How would anyone (or anything) even begin to calculate where the rocket needs to go or what it needs to do to get to its destination?

submitted by /u/NJDaeger
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Is there less oxygen in the atmosphere during the winter when there are no leaves on the trees?

Posted: 13 Oct 2017 01:28 PM PDT

what happens if two inbred people from different families have kids?

Posted: 13 Oct 2017 06:08 PM PDT

Does the small intestine stay stagnant in one position or do the tubes move around freely?

Posted: 13 Oct 2017 02:40 PM PDT

This question comes from something I saw on the television show House. During a surgery, House is checking a patient's intestines for granulomas and during the process he seemed to be moving the small intestine around a lot. Would it have been important for the doctors to place the small intestines in a specific way or would they have fine as long as there were no kinks? Do the intestines move around much during physical activities?

submitted by /u/A3Easy8
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Was the first sonic boom a surprise?

Posted: 13 Oct 2017 01:56 PM PDT

I'm having a weirdly hard time figuring out from google if the sonic boom from the first supersonic flight (Chuck Yeager in 1947) was expected or if it was a surprise and the physics explaining it came after.

submitted by /u/NightParade
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How is SF6, Sulphur Hexafluoride, possible as an atomic arrangement? How does it violate the octet rule?

Posted: 13 Oct 2017 03:47 PM PDT

Sulphur only has two valence electrons to form bonds. Can anyone explain how a Sulphur Hexaflouride molecule is able to exist in a stable state?

submitted by /u/Zakshdw
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How are bats' organs adapted to sleeping upside down?

Posted: 13 Oct 2017 08:46 AM PDT

I know why they sleep upside down and that tendons in their legs "cramp up" to make sure they hold on pretty tight. But how are their internal organs arranged? Doesn't blood flow to their brains like in humans turned upside down?

submitted by /u/Tame_Trex
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How is use of a Coulomb potential in solutions to the Schrödinger equation for single electron systems justified?

Posted: 13 Oct 2017 01:20 PM PDT

Atoms / ions with a single electron such as Hydrogen are often given as the most complicated systems for which analytical solutions of the (electronic) Schrödinger equation have been determined.

In deriving these solutions, the potential energy is invariably (in my searching) given by the Coulomb potential with a defined nucleus - electron vector.

This raises a few questions for me.

How is this justified in the context of a theory in which neither particle can have an arbitrarily well-defined position?

How has the Coulomb interaction been shown to apply to quantum mechanical systems?

Thanks for any insight you can share!

submitted by /u/mundegaarde
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What's the highest decibel sound we could possibly create?

Posted: 13 Oct 2017 06:01 PM PDT

Using current technology what would be the loudest sound we could muster? What would it take? Could we approach Krakatoa levels?

submitted by /u/CCGPV123
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If matter and antimatter annihilate in a vacuum, what form does the released energy take? Gamma? IR? X-rays?

Posted: 13 Oct 2017 12:11 PM PDT

If I were standing on the surface of the moon, and shot a gun parallel to the ground, how fast would the bullet have to go so that it fully orbited the moon just above the ground level?

Posted: 13 Oct 2017 08:11 AM PDT

And is the average velocity of a bullet from a standard rifle enough to do this?

submitted by /u/Waja_Wabit
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Why doesn't the blue light from the sky cast a blue shade on the ground?

Posted: 13 Oct 2017 12:42 PM PDT

I can understand in locations under direct sunshine--the light from the sun overwhelms any light refracting from the sky. But in locations that have a view of the sky but not the sun, why doesn't the light cast a shade of blue on everything?

submitted by /u/TrumpImpeachedAugust
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If mathematical models of artificial neural networks are so effective, wouldn't creating physical models of neural networks be even more effective?

Posted: 13 Oct 2017 07:38 AM PDT

Just wondering why this hasn't been done already?

submitted by /u/Perthie_Bertie
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Friday, October 13, 2017

How do we calculate numbers to an irrational exponent like x^pi?

How do we calculate numbers to an irrational exponent like x^pi?


How do we calculate numbers to an irrational exponent like x^pi?

Posted: 13 Oct 2017 04:54 AM PDT

I always understood that am/n = a times a m number of times and then take the nth root

but for irrational exponents, we just have an infinite non-repeating decimal that doesn't fall into that form.
I was thinking maybe for something like pi, calculators just round off somewhere and make the number something like 314159/100000 but I wasn't sure if it would overload the calculator first or something.

submitted by /u/ilikebutteryfries
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What are the specific values volcanologists would use to conclude that a major volcancanic eruption could be imminent at Yellowstone with the next 10-20 years?

Posted: 12 Oct 2017 07:10 PM PDT

Several news articles noted that yellowstone's 40mi wide caldera rose by 10 inches within the last seven years. These articles also noted that scientists believe conditions preceding an eruption could occur over as little as a few decades instead of over centuries as was previously thought. What are the expected values of gas emissions, seismic activities, deformation rates etc.. that would lead volcanologists to conclude that a major eruption of Yellowstone would be eminent within 10 to 20 years or less?

submitted by /u/imdabes
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Can a homogeneous mixture of two miscible liquids become non-homogeneous over time?

Posted: 13 Oct 2017 04:29 AM PDT

I work in the chemistry laboratory of sanitizer/soap manufacturing facility. On occasion, we have noticed some weird results when testing samples from the top of a tank compared to a sample from the bottom of the tank.

Mainly we noticed this with a product that is primarily water and isopropanol. I know that water and IPA are miscible. Would the difference in testing of a top and bottom sample be a result of improper mixing or do the two liquids form a gradient concentration mixture throughout the tank after a certain period of time?

submitted by /u/lxBATESxl
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What exactly makes aged wine better?

Posted: 13 Oct 2017 06:53 AM PDT

Could a helium balloon with a GoPro™ attached reach a high enough altitude to record the curvature of the earth?

Posted: 12 Oct 2017 11:39 AM PDT

Understandably, maybe not a regular store bought balloon, but my real question here is; couldn't "flat-earth" be disproven on a shoestring-budget?

submitted by /u/n0tL3nny
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Why does the Second Law of Thermodynamics include both a statement on Entropy and the impossibility of a completely efficient heat engine?

Posted: 13 Oct 2017 05:50 AM PDT

I'm having a hard time understanding how the two are related and why they are both grouped under the second law.

submitted by /u/miciah1_reddit
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What's the farthest a satellite can go into space and still send a reachable signal to earth?

Posted: 12 Oct 2017 09:27 PM PDT

Edit: Learning that I meant to ask about space probes and not an orbiting satellite.

submitted by /u/fisherdude123
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Can I have an "electricity leak" similar to how I can have a water leak in my house that will drive up my electric bill?

Posted: 12 Oct 2017 02:45 PM PDT

Would a very very cold bell sound the same as a very very hot bell?

Posted: 12 Oct 2017 02:01 PM PDT

Imagine two identical bells.

One is dunked in liquid nitrogen to cool it down.

The other is heated until it's red hot. It's not melting.

Each bell is then struck with a clapper.

Would they sound the same?

submitted by /u/murgleburgle88
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How is it possible to cool helium past the lambda point?

Posted: 12 Oct 2017 07:10 PM PDT

As the temperature of helium reaches the lambda point the specific heat approaches infinity.

Since your specific heat becomes so incredibly large, how is it possible to cool helium to below 2.17 degrees?

Additionally, since the specific heat tend to infinity, shouldn't helium at the lambda point (~2.17 K) have an near infinite specific heat, and thus have a static temperature independent of its energy?

submitted by /u/Vir_Maximus
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What is the different between Chaos and Randomness ?

Posted: 13 Oct 2017 12:00 AM PDT

As far as I know, chaos can be predicted as the result is based on initial conditions, while random is impossible to know, all we can do to random is to calculate the chance of the outcomes.

Sorry for my English.

submitted by /u/SPR-MKO
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What caused the different branches of Proto-Indo European (PIE) to have different order in grammar (subject verb object etc.)?

Posted: 12 Oct 2017 07:26 AM PDT

Does the probabilistic nature of quantum mechanics extend to non-quantum phenomena?

Posted: 12 Oct 2017 12:21 PM PDT

My understanding of this topic is very basic, but from what I can gather, everything (?) at a quantum level is described in a probabilistic sense rather than a deterministic one. Not because of measurement error, but for more fundamental reasons.

My question is this: does the uncertainty we observe in quantum mechanics manifest in any way in non-quantum phenomena? Are phenomena at a non-quantum level deterministic, as far as we can tell?

submitted by /u/Chicagodivemaster
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How is the "power" of dish soap measured? How can a company claim one of its products is "3 times as powerful" as another one?

Posted: 12 Oct 2017 04:33 PM PDT

There will be a geomagnetic storm on Friday 13th?

Posted: 12 Oct 2017 12:11 PM PDT

I'm reading in Spanish sites saying that there will be a geomagnetic storm on Friday 13th according to the russian site TASS, but there are no news in English

Is this a hoax?

submitted by /u/Yilku1
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Do aerosol droplets have the same concentration as the original bulk solution, irrespective of the droplet size?

Posted: 13 Oct 2017 12:37 AM PDT

Hello,

So, I think I have some guesses here, but I'm likely missing the correct search terms to feed google scholar.

When you're working with a spray, the easy assumption to make is that each drop is just a tiny sample of the bulk. If you have Xparts/L, that will just scale down to the micro or nano liter, is the hope. I trust that for the molecular level, but I'm working with something that has largish particles around the 10-30micron scale, and some sprays with a mean drop diameter around 100microns. There's a relation called Gibb's Isotherm that accounts for the "measured excess" at an interface in multi-component systems. That says, to me, one can expect you bulk to be somewhat inhomogenous. What does that mean for the drops one produces at an interface? Even just thinking of marangoni stresses, pinch off results in a radius of curvature one could expect to shuffle particles around.

Experimentally, the easy way to do this is probably stick beads into solution, spray on a glass slide measure drop size, evaporate, count particles. Has anyone done something like that? I cannot find it.

Thanks.

submitted by /u/Fizzix42
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Is there a condition that exists that would cause someone to perfectly understand English, but only be able to speak one word, like Hodor from GoT?

Posted: 12 Oct 2017 09:30 AM PDT

Watching GoT (finally) has made me curious if this is actually something that could happen, or if it was just something made up for the story.

submitted by /u/vayperwayve
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Does There Exist A Series Smaller than the Harmonic Series that STILL Diverges?

Posted: 12 Oct 2017 12:34 PM PDT

Is there such a thing, or is the Harmonic series the smallest series we know of that still diverges? I'm not exactly sure if I'm phrasing the question properly, in the sense that it may not be exactly clear what "a series smaller than the harmonic series" even means, right?

I mean, there's an argument to be made that the harmonic series is greater than the series:

1/2 + 1/2 + 1/2 + 1/2 + 1/2...

which clearly diverges, right? Because they can be re-written as:

1/2 + 1/4 + 1/4 + 1/8 + 1/8 + 1/8 + 1/8...

1/2 + 1/3 + 1/4 + 1/5 + 1/6 + 1/7 + 1/8...

But is there some way to describe how "large" a series is? Or how quickly it diverges? And if there is, is there a series that is "smaller", or diverges slower, but still diverges?

submitted by /u/garrettj100
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When we watch videos on YouTube do they get temporarily stored on the hard-disk or phone's storage or are they just stored in the RAM for some time ?

Posted: 12 Oct 2017 11:36 AM PDT

How fast does Kinetic energy travel?

Posted: 12 Oct 2017 10:50 AM PDT

To preface this question I wanted to say that I'm not sure if kinetic energy is the correct term.

As it stands, I'm under the impression that the speed of light is the fastest anything can travel. So in a completely hypothetical situation, if we were to build a tube(cylinder) that held a single file line of marbles (all being in direct contact) that stretched to the moon. How long would it take a marble on the receiving end to be pushed out of the tube when a marble on earth was pushed into the tube?

As a follow up, if there is a delay, how does this work?

submitted by /u/Koalchemy
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