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Monday, December 18, 2017

A 5 foot section of railroad rail does not seem very flexible but a 200 foot section appears to be as flexible as a noodle with bends under a foot. How does longer length make it more flexible?

A 5 foot section of railroad rail does not seem very flexible but a 200 foot section appears to be as flexible as a noodle with bends under a foot. How does longer length make it more flexible?

A 5 foot section of railroad rail does not seem very flexible but a 200 foot section appears to be as flexible as a noodle with bends under a foot. How does longer length make it more flexible?

Posted: 17 Dec 2017 08:49 PM PST

How are there lakes in the bottom of the ocean?

Posted: 17 Dec 2017 11:00 AM PST

Can Dogs Count?

Posted: 18 Dec 2017 03:14 AM PST

I was watching a video in which a labrador father is teaching his pups how to swim. Great content, very adorable. But at one point, they all run off leaving one slightly worried and confused pup behind.

But after a few seconds (long enough for the daddy dog to realise) the rest of them come back to collect the lost puppy before taking off again.

So does the daddy dog just know that one of his dogs is missing, or is he keeping track of how many he can see? Is this a visial, cognitive process of "Let's re-count the puppies so I know none of them are lost or in danger" or is it more instinctive than that?

Thanks nerds.

submitted by /u/TheresanotherJoswell
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Which symmetry is related to the conservation of mass in classical mechanics?

Posted: 17 Dec 2017 04:43 PM PST

According to Noether theorem every symmetry of a problem leads to a conservation of a quantity:

Time evolution symmetry - Energy conservation

Spatial translation sym- Momentum conservation

Rotation - Angular momentum

U(1) gauge - electric charge

Even Galilean translation - Center of mass displacement conservation

Which one is related to conservation of mass? I know it is not conserved in special relativity but Noether applies also to classical mechanics.

submitted by /u/MaoGo
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How can audio be sped up without increasing in pitch?

Posted: 17 Dec 2017 01:53 PM PST

For example, say that you increase the speed of a recording of a voice. Normally, the pitch of the voice would increase as the sound gets sped up, but some software allows you to increase the speed of an audio file while maintaining the pitch. What's the difference between these two functions regarding how the sound waves are behaving?

submitted by /u/Jnastasi110
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Why does stuff get preserved in amber?

Posted: 17 Dec 2017 07:39 PM PST

What prevents the immune system from attacking useful bacterias in the intestines?

Posted: 17 Dec 2017 08:43 AM PST

What is the difference between effective nuclear charge and core nuclear charge?

Posted: 17 Dec 2017 07:50 PM PST

What is the meaning/mechanism behind IR drop in supercapacitors?

Posted: 17 Dec 2017 06:25 PM PST

When measuring internal resistance in a supercapacitor you use the IR drop, which is measured when the current direction is switched. What is the meaning of this voltage drop? Why is the voltage of the cell different depending on direction of current?

submitted by /u/popkornking
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Is there a "filter" that can shift infrared light into the visible spectrum?

Posted: 17 Dec 2017 10:19 AM PST

As far as I know, night vision goggles that are based on IR use a camera and a display for this "conversion".

Is there a different way to make the infrared visible?

submitted by /u/mbasl
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What determines an automatic weapon's rate of fire?

Posted: 17 Dec 2017 11:18 AM PST

Why are world maps drawn as if we were looking at the Earth from above and not from below?

Posted: 17 Dec 2017 10:28 PM PST

I thought it made sense because we have satellites but maps have been drawn like this since way before planes were invented.

submitted by /u/mittluva
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What causes interference noise while touching metal with unplugged headphone jack?

Posted: 17 Dec 2017 04:16 PM PST

So yeaterday after putting on my in-ear headphones i accidentally touched a piece of metal and it made a interference noise. Just like the noise in the radio.

Where does the energy come from to generate that noise and why metal.

submitted by /u/Mongolete
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Can somebody else listen to what I'm listening to if I'm using a bluetooth headset?

Posted: 17 Dec 2017 05:34 PM PST

With more and more phones ditching the 3.5 mm audio jack, it seems like we're headed into an age dominated by bluetooth earbuds and headsets. Is this a privacy concern? Can a 3rd party that wasn't present during the device pairing process come by and hijack the audio coming out of my phone (or worse)?

submitted by /u/17jwong
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What's the difference between Cocaine and Crack Cocaine, and what's a freebase?

Posted: 17 Dec 2017 03:03 PM PST

What type of noise does a hand held blow dryer produce?

Posted: 17 Dec 2017 04:38 PM PST

I know there are different names for different types of (mathematical) noise such as white, brown, pink noise etc. Is there one of those types that comes close to the noise profile that a blow dryer produces?

submitted by /u/diamondboyboy
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What is a food allergy and why can’t I “get use” to the food?

Posted: 17 Dec 2017 02:22 AM PST

I have peanut allergies and have countlessly eaten many foods containing peanuts, why doesn't my body just not respond to the peanuts?

submitted by /u/CryneXera
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Sunday, December 17, 2017

How are drill bits that make drill bits made? And the drill bits that make those drill bits?

How are drill bits that make drill bits made? And the drill bits that make those drill bits?

How are drill bits that make drill bits made? And the drill bits that make those drill bits?

Posted: 17 Dec 2017 02:52 AM PST

Discovery Channel's How It's Made has a segment on how drillbits are made. It begs the question how each subsequently harder bit is milled by an ever harder one, since tooling materials can only get so tough. Or can a drill bit be made of the same material as the bit it's machining without deforming?

submitted by /u/ssinatra3
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How long does it take for every brain cell to die after oxygen is cut off?

Posted: 16 Dec 2017 08:53 AM PST

Edit: I found this paper indicating brain cell life at 8 hours after but, unfortunately, that's all it tells us. It doesn't tell us whether or not some of the cells may stay alive longer.

Quote from the paper:

Animal models for human neurological and psychiatric diseases only partially mimic the underlying pathogenic processes. Therefore, we investigated the potential use of cultured postmortem brain tissue from adult neurological patients and controls. The present study shows that human brain tissue slices obtained by autopsy within 8 h after death can be maintained in vitro for extended periods (up to 78 days) and can be manipulated experimentally. We report for the first time that 1) neurons and glia in such cultures could be induced to express the reporter gene LacZ after transduction with adeno-associated viral vectors and 2) cytochrome oxidase activity could be enhanced by the addition of pyruvate to the medium. These slice cultures offer new opportunities to study the cellular and molecular mechanisms of neurological and psychiatric diseases and new therapeutic strategies.

submitted by /u/Banda8820
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Is there any correlation between certain names, and behavior? Are certain names more likely to succeed than other names? I imagine some names might cause bullying more than others. But I’m more curious if there are any names with a positive social correlation.

Posted: 16 Dec 2017 12:02 PM PST

What makes something “microwave safe” and another similar material not safe?

Posted: 16 Dec 2017 08:35 AM PST

I know some heat up and that makes them unsafe, but why do some materials heat up in a microwave and others don't?

submitted by /u/Severse_Rhycology
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I have often read of interspecies adoption and nursing of the adopted young, how does an animal produce milk for young that is not their biological offspring?

Posted: 16 Dec 2017 08:20 AM PST

Why does ribbon curl?

Posted: 17 Dec 2017 06:24 AM PST

So I'm a physicist and mathematician but when wrapping presents my daughter asked me something I couldn't answer. Why does ribbon curl when you drag a sharp edge along it? So I'm asking any materials scientists out there.

Edit: Can't figure out how to flair this mobile, sorry.

submitted by /u/NoBooksForYou
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Why are the mirrors on the newer telescopes shaped like hexagons?

Posted: 16 Dec 2017 09:21 AM PST

I've seen in the news that there's going to be a big telescope in Chile, or Argentina? Can't remember. Anyways, the mirrors are tons of small hexagons. Why this shape and not squares or triangles?

submitted by /u/Starspary
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How do surgeons place back organs like intestines?

Posted: 16 Dec 2017 05:01 AM PST

I have seen in some films and series how they take the intestines out of the chest and move them but I have never seen how they put them back. Is there any way of doing it or do they just place them back and they recover their shape by themselves?

submitted by /u/Calcirium
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Why does oxygen have a lower melting point than nitrogen?

Posted: 17 Dec 2017 06:57 AM PST

To my knowledge it seems that oxygen should have a higher melting point because it has more electrons and will therefore stronger London/van der waal forces giving it a higher melting point. Is this wrong or is there another factor

submitted by /u/wiggiebob
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Can electromagnets produce a field of any shape? Are there limits to this?

Posted: 17 Dec 2017 06:37 AM PST

Is it possible to create an electromagnetic array such that the field generated would produce an expected shape of any variety? What I envision is something akin to a monochrome LCD panel, except the "pixels" are peaks that pass a certain threshold of strength. Is this possible, and if so, are there limits in terms of size of apparatus that could produce this vs amplitude, and are there any properties that inhibit shrinking this down to the micrometer level? What I am thinking is of a programmable 1000x1000 grid of peaks at 10 micrometers2. Can this be done?

submitted by /u/accidentalginger
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How are electrons "high energy"?

Posted: 17 Dec 2017 12:18 AM PST

I read in this AP bio book that as an electron is passed though a series of increasingly electronegative protein pumps to pump H+ across a membrane. The electron is no longer high energy after doing so. Does this mean that an electrons potential energy is measured by it's association with an electronegative molecule/particle. such as in a molecule that has C and O sharing electrons, the closer the electrons are to the oxygen (Which is more electronegative than carbon) per the amount of valence electrons is the potential energy of that molecule? Is this redox in a nutshell?

~A sophomore in high school

submitted by /u/AlacasterSoi
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Do radioactive metals decay faster when molten?

Posted: 16 Dec 2017 11:32 PM PST

Is there any difference between vertical or horizontal pupils in animals?

Posted: 16 Dec 2017 10:28 AM PST

Does one angle have an advantage over the other?

Also, wtf about square pupils in goats? Is there any advantage/need for not circular pupils?

submitted by /u/acrowsmurder
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What is the highest altitude we have ever found living organisms?

Posted: 16 Dec 2017 06:00 AM PST

Recently I heard that the Griffin Vulture can reach altitudes of 10,000 meters and that several species of geese can fly over Mount Everest. However these are all large animals far from the most extreme of Earth's life, extremophiles. Is there living bacteria in the upper stratosphere? If so, how did it get there? Just how high have we found it? Can it sustain it's self up there indefinitely?

submitted by /u/GalliumGames
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Why do we need rectifiers?

Posted: 17 Dec 2017 12:19 AM PST

Why cannot appliances work on A.C. as the polarity change is very quick?

submitted by /u/thewhitenibba
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Why is the rest of the moon still slightly visible during a crescent moon?

Posted: 16 Dec 2017 02:25 PM PST

This photo shows how the rest of the moon not facing the sun is still visible. Could it be reflection from the earth or other sources?

submitted by /u/ssinatra3
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Do meerkat colonies suffer from inbreeding issues?

Posted: 16 Dec 2017 07:30 AM PST

I would think this is more of Zoology but it isn't an option for the flair.

As territorial creatures, I'd expect meerkats to rarely accept strangers into their community, which would ultimately mean that they would just be mating with each other, yes? If this is the case, I would think that there would be massive inbreeding after a few generations and a severe lack of genetic diversity. Is this the case? Or do they in fact actually open up their community to outsiders more often than I assumed?

submitted by /u/thehottestmess
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What happens to the air inside your intestines when you are on a flying airplane?

Posted: 16 Dec 2017 08:30 AM PST

How do "airless tires" work?

Posted: 16 Dec 2017 08:58 AM PST

I get how the air pressure in an inflated tire can keep it from collapsing or deflating under the weight of a car, but how do airless tires manage to produce that much pressure without the use of air?

submitted by /u/Dilplok
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Why does a passing car horn reduce in pitch?

Posted: 16 Dec 2017 10:11 PM PST

This might be a dumb question, and I apologize if 'physics' is the wrong flair for this question, but I've heard this quite a few times and have been curious about it. Why does a passing car horn reduce in pitch rather than just decibel level? If I yell a G note when far away from someone, do they still hear a G, or do they hear a lower note?

submitted by /u/Jakeenes
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If two elements are combined, what happens to their individual half-lives?

Posted: 16 Dec 2017 03:36 PM PST

When in a betting pool for a series of sports matches, is the optimal strategy choosing the probabilistic winners of each individual match (e.g., based on Vegas odds), or does that strategy, due to its expected popularity among other competitors in the pool, make it not optimal?

Posted: 16 Dec 2017 07:45 AM PST

Assuming a large scale wagering pool of thousands of individuals. Assuming Vegas odds are the true odds, and that odds are not typically 50/50, though they can be.

E.g., in a March Madness (U.S.) bracket with 10,000 people, is the optimal strategy choosing the favorites? Or does this strategy welcome increased competition.

submitted by /u/resumates
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Saturday, December 16, 2017

Why do airplanes need to fly so high?

Why do airplanes need to fly so high?

Why do airplanes need to fly so high?

Posted: 15 Dec 2017 12:10 PM PST

I get clearing more than 100 meters, for noise reduction and buildings. But why set cruising altitude at 33,000 feet and not just 1000 feet?

Edit oh fuck this post gained a lot of traction, thanks for all the replies this is now my highest upvoted post. Thanks guys and happy holidays 😊😊

submitted by /u/peterthefatman
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Can light and sound affect each other?

Posted: 16 Dec 2017 04:54 AM PST

What happens when microwaves hits metal?

Posted: 16 Dec 2017 03:45 AM PST

I know as much as microwaves makes molecules vibrate, and certain objects heat up faster than other, due to amount of liquid? I also know that metals reflect the microwaves, but not why and what happens to the metal..

My real question.. would it be safe to crumble aluminum foil and put it on the bottom of a bowl filled with water/soup, to speed up the heating of the liquid?

submitted by /u/Jerkalerka
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If we were able to accelerated a spaceship/probe to a fraction of the speed of light would space dust start punching tiny holes through it?

Posted: 15 Dec 2017 02:22 PM PST

It seems that at very high speeds even minute particles in space could become dangerous. Would this make some sort of shield a necessity?

submitted by /u/HoboOperative
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How does binary convert into light waves in optical cables?

Posted: 15 Dec 2017 07:35 PM PST

Why do cable TV providers still need cable boxes which stream via coaxial cable?

Posted: 15 Dec 2017 09:23 PM PST

With the advent of Apple TV et al, as well as online viewing apps available from Spectrum (and I assume others), why haven't cable TV providers made their own IoT device that does the same thing as my cable box? And for that matter, why doesn't that functionality come built in to my TV?

submitted by /u/real_namreeb
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How do we know the axial tilt and rotation of planets in our solar system?

Posted: 15 Dec 2017 10:48 AM PST

Do men have hormonal cycles?

Posted: 15 Dec 2017 06:10 AM PST

And if so, what are they like and what causes them?

Bonus: what effect does the moon have on hormonal cycles, both female and male?

submitted by /u/DetainTheFranzia
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What is the meaningful distinction between nuclides and isotopes?

Posted: 15 Dec 2017 12:31 PM PST

I've read several different articles on this, talked to nuke engineers, and really just failed to receive a consistent and satisfactory answer. It almost seems like "nuclide" is a preferred term for the nukes while "isotope" is preferred by chemists. I understand very well the concept of elements, atomic masses, etc. I just want to make sure I'm using the correct terminology.

For instance, is it proper to refer to U-238 as an isotope of uranium, or is U-238 a nuclide? I've heard the former but very rarely the latter. Are both valid? When would one be valid and the other not?

Thanks

submitted by /u/Kestrelio
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[PHYSICS] What other elements (Also hypothetical Elements e.g. Superactinoides) are in theory usable in atomic bombs and what would be their possible radioactive damage to environment/organisms?

Posted: 15 Dec 2017 03:45 PM PST

Hello!

I hope I'm posting this in the right sub-reddit; if that's not the case I apologise.

First off: I'd like to point out that this question is tied to me writing a fantasy/sci-fi book. So, accuracy of course would be great, but even "wild" theories are welcome! I just want to give some sort of explaination for what happens in my book instead of just far-fetching things and tell the reader "Oh well. It's just the way it is." Also my english is a bit rusty, so bear with me. Also I'm welcoming any other idea that revolves around a logical explaination for a radioactive infestation of the planet.

To cut things short: Could it be possible to create a implosion type or gun-type atomic bomb with an undiscovered element or any other element except Uran/Plutonium?

And if so: Is there one element that "infests" the environment for only 200-500 years?

I read that Neptunium is a solid canidate to build atom bombs with and just due to historical events scientists chose not to work with this element.

Book: New element found -> Crafty bomb -> Makes big boom -> Big scale enviromental desaster -> hello mutants -> yeay after ~250 years no more radiation!

I know y'all probably fed up with "fallout scenarios" when it comes to literature, haha! Please help me out though.

Thanks in advance guys!

submitted by /u/Klavierente
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Why do atomic chain reactions not happen in nature?

Posted: 15 Dec 2017 04:15 PM PST

1 in 100 or so Uranium atoms are U-235, which is the type of Uranium necessary to cause an atomic chain reaction. If a random neutron flying through a Uranium deposit hits U-235, wouldn't that risk the start of a fission chain reaction? If so, why prevents such reaction from happening in nature?

submitted by /u/BackToAqaba
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If you have a perfectly thermally insulated container and add equal amounts of liquid at 0C and 100C, does the thermal equilibrium always occur at 50C?

Posted: 15 Dec 2017 11:42 PM PST

Whats the possibility of gaining momentum by dry firing a bow in space?

Posted: 16 Dec 2017 03:20 AM PST

Does the probability of pregnancy change depending on the genetic distance between two human parents?

Posted: 15 Dec 2017 08:55 AM PST

I understand that the greater genetic difference between two parents often results in hybrid vigor, making the offspring more genetically "fit". I've read studies that imply cancers are less likely, immunity to disease is better, and many other benefits when a human (and really, most other animals) is an offspring of genetically diverse parents.

I was wondering, though, if that means there is some sort of trade off. Is the chance for pregnancy lower with "mixed race" couples than "same race"?

Also (side question), does hybrid vigor tend to be more of a benefit post birth or have there been any studies that show genetic difference has an effect on reducing the chances of complications during pregnancy as well?

TL,DR: Do pregnancies that benefit from heterosis have a better or worse chance of fertilization, or does it not matter?

submitted by /u/MisterFlibble
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Why are the edges of shadows fuzzy and not sharp?

Posted: 15 Dec 2017 09:01 AM PST

Why is it the energy levels in an infinite well have a spacing between them with a squared pattern, but in a harmonic oscillator they are linearly spaced? What is the physical meaning behind this?

Posted: 15 Dec 2017 07:38 AM PST

What gives stars their color?

Posted: 15 Dec 2017 11:16 AM PST

I've heard a lot about stars having different colors like red giants or white dwarfs. From what I understand, a star is just a huge fusion reactor that fuses hydrogen to produce helium. What is different about these stars that changes the color?

submitted by /u/jacpot19
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An empty refrigerator vs a full refrigerator - is there a difference in power usage?

Posted: 15 Dec 2017 08:54 PM PST

All things equal besides content, if I had an empty refrigerator and I had a refrigerator full of beer would there be a difference in the amount of energy required to keep the refrigerator at the same temperature?

submitted by /u/RGN_Preacher
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Can you reflect presumably a "Death Star" Laser using a simple mirror?

Posted: 15 Dec 2017 01:25 PM PST
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