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Tuesday, April 24, 2018

How does hair hold onto water so well?

How does hair hold onto water so well?


How does hair hold onto water so well?

Posted: 23 Apr 2018 04:47 PM PDT

I shower in the evening and my hair is still wet the next day

submitted by /u/TheGirlKing
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Why are rainstorms frequently accompanied with lighting, but snowstorms/blizzards rarely (never?) have lightning?

Posted: 23 Apr 2018 04:26 PM PDT

In a rotating black hole, what is rotating?

Posted: 24 Apr 2018 02:30 AM PDT

Just something that crossed my mind recently, since the horizon isn't made up of anything. What is the rotating. Or is it just a way to allow for the conservation of angular momentum without having to go inside the BH with our current understanding?

submitted by /u/Michkov
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What’s happening when cloths are bleached by the Sun?

Posted: 24 Apr 2018 04:09 AM PDT

Why does Miso paste in Miso soup clump up the way it does?

Posted: 24 Apr 2018 05:56 AM PDT

How easy is it to find a polynomial function of degree n to match n value-pairs?

Posted: 24 Apr 2018 05:30 AM PDT

I have a dim memory, that my math teacher once said, he can "easily" find such a polynom. Doing that with value pairs (x,y) where they have a form of (x,0) is trivial, so I think it could be possible to do manually. Do you know of any viable method, or did my memory play a trick on me?

submitted by /u/errolo
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What does a monogamous bird do when his partner die ?

Posted: 23 Apr 2018 11:59 AM PDT

Why does glide reflection have its own symmetry type, when it's just a combination of two other types (reflection and translation)?

Posted: 23 Apr 2018 09:36 PM PDT

What would happen if we were able to cool our computers to 0K?

Posted: 24 Apr 2018 06:14 AM PDT

Would they become less power-hungry? Make less heat?

submitted by /u/adamski234
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The label on my food says there are tens of kilojoules of energy per serving. Why can only our bodies use this energy and not for general power use?

Posted: 23 Apr 2018 07:42 PM PDT

How does a doctor determine "you have a 5% chance of living" or x% chance of walking again, seeing again, and so on?

Posted: 23 Apr 2018 05:43 PM PDT

Is it just a coincidence that the charges of protons and electrons happen to be equal in magnitude?

Posted: 23 Apr 2018 04:27 PM PDT

How did they set the exact moment (not duration) of the second pulse of Universal Time (UTC)?

Posted: 23 Apr 2018 03:50 PM PDT

How did they find the exact nanosecond to place the second pulse? Is it set exactly to the split second from solar mean time? Or did they just find an arbitrary moment approximately about mean solar noon? Why isn't the time 0,5 second ahead, or a half minute?

submitted by /u/Navstar27
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Why did earth's debris become a moon but Saturn's became rings?

Posted: 23 Apr 2018 04:40 PM PDT

How did Olympus Mons get so big?

Posted: 23 Apr 2018 02:47 PM PDT

When you put on a large amount of weight and your skin surface area increases, do you gain more hair follicles or does the space between each follicle just get bigger?

Posted: 23 Apr 2018 03:57 AM PDT

Does Heisenberg's uncertainty principle suggest that you can determine velocity and position to good precision if you don't know the particle's mass? Is there even any situation where that could come up?

Posted: 23 Apr 2018 12:29 PM PDT

How many photons do we see per star?

Posted: 23 Apr 2018 11:11 PM PDT

Some stars seem brighter than others. At first thought, I would think that we see more photons from it. But then I think about how wide of an angle a star is shooting photons in all direction... and how far we are away, and the very very pricise angle needed to hit our eyes. I think the number of photons being released by a star has to be astronomical even if just 1 or more hit our eyes.

I bet the math is beautiful on how we estimate how many photons that a star releases over a time period.

submitted by /u/goodnewsjimdotcom
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Why is favism (G6PDD) more likely to occur in populations that have historically consumed fava beans?

Posted: 23 Apr 2018 06:31 PM PDT

I read about fava beans and see they've historically been a staple-food for mediterranean and north african peoples, and then I read about favism and see that mediterranean and north african peoples are more genetically predisposed to G6PDD.

And I wonder...why?

submitted by /u/kreblator
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Can aerodynamic lift be used to increase a road vehicle's fuel efficiency?

Posted: 23 Apr 2018 03:54 PM PDT

Downforce keeps cars like the Camry "grounded to the ground," are there any practical or theoretical applications of a car's aerodynamics being used to produce minimal or moderate lift at highway speeds?

submitted by /u/DowntubeShifts
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What shape(s) are black holes?

Posted: 23 Apr 2018 11:59 AM PDT

Typically -- we see black holes referred to as a sinkhole of sorts, with a ring that funnels to a singularity.

Do we have a definitive concept of black holes, and what their actual shape is? If they're a small ball with a central singularity, or in-fact a ring shape that just orients based on their creation?

submitted by /u/shiroun
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What's is the evolutionary history of opossums? How are the related to Australian marsupials? Why are there so few marsupials in North America?

Posted: 23 Apr 2018 06:02 AM PDT

How are we trying to find dark matter if we don't know what it is?

Posted: 23 Apr 2018 07:36 PM PDT

Monday, April 23, 2018

How is it so that several (all?) mammals grow and lose a set of "baby teeth" before growing their final dentition? Why stop at two sets when other vertebrates such as sharks regenerate their teeth constantly?

How is it so that several (all?) mammals grow and lose a set of "baby teeth" before growing their final dentition? Why stop at two sets when other vertebrates such as sharks regenerate their teeth constantly?


How is it so that several (all?) mammals grow and lose a set of "baby teeth" before growing their final dentition? Why stop at two sets when other vertebrates such as sharks regenerate their teeth constantly?

Posted: 22 Apr 2018 08:36 PM PDT

How does hydrogen embrittlement work?

Posted: 23 Apr 2018 04:57 AM PDT

If placed in a controlled environment, do trees that normally undergo seasonal leaf Abcission stop losing their leaves?

Posted: 22 Apr 2018 03:40 PM PDT

How do our eyes avoid being commonly infected through things like rubbing our eyes or the pollutants in the air?

Posted: 22 Apr 2018 04:26 PM PDT

Whats the difference between an explosive, a propellant and an accelerant?

Posted: 23 Apr 2018 12:30 AM PDT

I'm a bit confused about the differences and whether individual substances might sometimes overlap in function depending on how they're used or if perhaps some are subcategories of another.

submitted by /u/infamousnexus
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Would it be possible to have a ball of electrons?

Posted: 22 Apr 2018 11:14 PM PDT

Forgive me i have no way to phrase that doesnt make me sound uneducated. Im working on writing a story for another thread, r/HFY and this as an idea for"faster than light travel"

Obviously I'm no scientist, but like I said I'm just trying to slap some science into my story.

Would it be possible to contain electrons without a neutron or proton to bond to, in one mass? Enough of them perhaps that this mass, would have it's own gravitational pull.

Further more what happens if an object were to be pulled continuously into this gravity? Would it just continue accelerating or is there a cut off point?

submitted by /u/FaultlessBark
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Does Ocean Salinity Drop During/After a Rainstorm?

Posted: 22 Apr 2018 11:05 PM PDT

I was listening to the "Water's Not Wet" guy, and it got me thinking. The ocean may not "get wet" but rainwater and ocean water are very different in composition. The ocean is salt water and rain is fresh water (or at least has less salinity than the ocean). So my question is this: Does the salinity of the surface of the ocean drop during/after a rainstorm? If so, by how much, and how deep? (Obviously, the bottom of the ocean wouldn't be affected much/quickly by rain at the surface.) Is this something that can be measured, and has it been?

If it doesn't change much, is it due to the fact that the ocean is so large that a rainstorm's worth of water won't affect the salinity, even locally?

submitted by /u/AdmiralMemo
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Statistical Regression: Why don't we care about the t-stat / p-value for the intercept term ?

Posted: 23 Apr 2018 12:40 AM PDT

For doing linear regressions, we do care about the t-stat/p-value for coefficients for the independent variables because we would like to see if the estimated coefficients are significantly different from zero.

From what I have heard, we don't care much if the t-stat/p-value for the constant/intercept term indicates that the estimated value of the intercept is not significantly different than zero.

Why exactly is this though? The value of the intercept is still used in our regression formula, so wouldn't we care about its value too? (Not sure if this is the appropriate question to ask?)

Thanks!

submitted by /u/MAIRJ23
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Do nocturnal animals prefer sleeping conditions that are dimly lit or bright in contrast to humans which prefer dark conditions?

Posted: 22 Apr 2018 09:57 AM PDT

How for down into the mantle do we have to go before the temperature is hotter than the surface?

Posted: 22 Apr 2018 08:55 PM PDT

Is this depth consistent at all latitudes?

submitted by /u/iarrrrpirate
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Would objects orbiting Earth, such as space debris, satellites, the ISS, be hot or cold to the touch?

Posted: 22 Apr 2018 02:14 PM PDT

Either way, how hot or cold would the object be that has been orbiting Earth for years?

submitted by /u/WeslyCrushrsBuffant
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Are women born with all their eggs?

Posted: 22 Apr 2018 05:18 PM PDT

I've always been told that women are born with a set number of eggs and once they run out they're gone. Recently I've also heard that this isn't true. So, are women born with all their eggs? Do we know for sure?

If you could link any articles of studies that would be great!

submitted by /u/RigbyAtNight
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How can we tell if someone we can’t see is shouting from far away or whispering close to us?

Posted: 22 Apr 2018 12:41 PM PDT

Ignoring echo from being in a room how do we know.

submitted by /u/bobby_blobby
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How do phones keep cool with small heatsinks and no fans?

Posted: 22 Apr 2018 10:16 AM PDT

[Medicine] What leads a body to reject or accept donated organs?

Posted: 22 Apr 2018 11:53 AM PDT

Why are shadows casted from objects more crisp depending on how far the object is from the ground?

Posted: 22 Apr 2018 11:50 AM PDT

If the human body has evolved over millions of years to swell up in response to an injury, why are we instructed to apply ice to prevent our evolutionary swelling response?

Posted: 22 Apr 2018 04:14 AM PDT

How does a train engine, pulling miles of cars and many tons of load, get enough traction to actually move everything?

Posted: 22 Apr 2018 08:33 AM PDT

What are public and private keys and what do they do for a server when transferring information?

Posted: 22 Apr 2018 05:02 PM PDT

What is the shape of a transmissions wave? Can this shape be changed? Can motion significantly affect the shape?

Posted: 22 Apr 2018 10:55 PM PDT

This is probably in both the physics department. Consider a perfectly straight line separating point A and B. The line is significantly lengthy, but not infinite. There is a car that will travel from A, to B, carrying a transmitter emitting a microwave. I'm automatically assuming that the transmission of the car, while stationary, is perfectly spherical.

However, when the car starts moving forward what happens to the shape?

  1. Does the shape of the transmission's microwave be cone shaped with the tip of the cone being the car itself and the widest base of the cone be point A?

  2. Let's introduce a new point, C. As the car moves forward, so does C. Point C can be anywhere ahead of the car. If you are at point C, how would you observe the shape of the microwave? Would it look like a cone to you? Or a perfect sphere with the car at it's center?

For the sake of this terribly worded exercise, please assume the car can move very fast, just not faster than the speed of light. Basically, what is the shape of a microwave, and does motion affect it?

submitted by /u/Xerxys
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Are there earthquakes in other planets?

Posted: 22 Apr 2018 09:08 PM PDT

Why wouldn't they be? What makes our planet so special to have tectonic plaques that produce earthquakes? Or is that why there are not earthquakes in space, as there is nowhere their earth or, whatever their soil is made of, move?

Maybe this is a very stupid question, but I guess... why wouldn't they be?

submitted by /u/Poch391
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Why don’t we sneeze in our sleep?

Posted: 22 Apr 2018 11:00 AM PDT

Studies have shown that small movements in the throat occur during an internal dialogue--does that happen when music plays in your head, too?

Posted: 22 Apr 2018 04:28 AM PDT

The movements are similar to the ones used during speech and even certain parts of the brain are active both during the internal dialogue and speaking (IIRC).

But what about the music that plays in your head? Be it some earworm or a personal favorite, most people have music in their head at one time or another throughout the day. Does the same activity in the brain and throat occur with the music and the vocals? What about the memories of someone speaking?

submitted by /u/WadeEffingWilson
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Sunday, April 22, 2018

How does a master key work?

How does a master key work?


How does a master key work?

Posted: 22 Apr 2018 03:45 AM PDT

Why does sunburnt skin feel hot to the touch?

Posted: 21 Apr 2018 03:42 PM PDT

Been sunny in the uk and ouch

submitted by /u/thelongpartofaspoon
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When you shake up a carbonated drink, where does the pressure go once it’s ‘settled’?

Posted: 21 Apr 2018 06:43 PM PDT

What makes people see tennis balls as either yellow or green?

Posted: 22 Apr 2018 05:15 AM PDT

I talked to a friend and we came to different conclusions as to what color a tennis ball is. How come there is a difference at all?

I first assumed it was like the dress but there was only ever one photo with questionable background while pretty much everyone of us has seen a tennis ball in more than one occasion and context.

submitted by /u/bluefirex
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Air molecules travel at 1000 mph. Can we harness that kinetic energy?

Posted: 22 Apr 2018 12:27 AM PDT

Air molecules are travelling at around 1000 mph at room temperature. Why is it not possible to harness all that kinetic energy to produce electricity?

I guess the answer is that for every molecule travelling in one direction, there is another travelling in the opposite direction. Could a structure be designed to trap more energy from molecules travelling in one particular direction? Eg nano-scale V shapes. Air molecules hitting the top of the V would have to bounce back out again, imparting a lot of energy. Molecules hitting the underside would only need a small deflection, imparting less, leading to a downward force on the V.

submitted by /u/Freeewheeler
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Do mental illnesses run in families? Will they be the same mental illness or can they vary between each offspring?

Posted: 21 Apr 2018 10:32 PM PDT

How were the subduction zones discovered and observed?

Posted: 21 Apr 2018 05:30 PM PDT

In my chemistry class yesterday we learned about the pathlength of gas molecules in a gas at STP. What is the pathlength of interstellar hydrogen? What about the intergalactic medium?

Posted: 22 Apr 2018 12:09 AM PDT

What factors affect the orbit of our sun around the galaxy?

Posted: 21 Apr 2018 03:30 PM PDT

Our solar system circles the milky way, but it also "bops" up and down in relation to the plane of the (mostly flat) galaxy. Are we orbiting something massive besides the galactic center of mass? Or are we "oscillating" back and forth through a stable position, destines to come to a rest at some point in the future? Is the current consensus that this movement has some effect on our climate or the risk of impact from celestial objects, or that it is mostly meaningless?

submitted by /u/OlfertFischer
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Why do images on a monitor become negtive when viewed from a certain angle?

Posted: 21 Apr 2018 01:05 PM PDT

How far in advance can we predict a major tectonic event?

Posted: 21 Apr 2018 02:54 PM PDT

Is it even possible to guess based off other events that have happened?

submitted by /u/Nemnexous
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What kind of PRNG algorithm(s) are used by supercomputers running simulations for things like weather modeling or orbital dynamics?

Posted: 21 Apr 2018 08:25 PM PDT

For a specific example, what do ECMWF use in their tropical cyclone simulations? Or, amm I totally off base thinking these simulations need the speed of a PRNG?

submitted by /u/WildWildSouth
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In many-worlds interpretation, when exactly branchings happen?

Posted: 21 Apr 2018 11:25 PM PDT

According to my youtube-video-level understanding of M-W, the universe splits each time particles interact, forming ever growing tree of branches. But isn't the concept of simultaneity undefined in special relativity, making it impossible to form tree with clearly ordered branches? Also, isn't the concept of "particles interacting" just a special case of continuous wave functions interacting? So how do we define branching when every wave function interacts with every other wavefunction, to different degrees, at each moment?

submitted by /u/NotGonnaCooment
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Are there physical or practical limits to how much power batteries can store in a given amount of space?

Posted: 21 Apr 2018 07:21 PM PDT

Why doesn't concentration affect the rate constant?

Posted: 21 Apr 2018 02:47 PM PDT

From the arrhenius equation, it seems the A (or frequency factor) is partially describing the frequency of collisions. Wouldn't A increase with an increasing number of one or both of the reactants?

submitted by /u/readlock
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How is fuel efficiency defined?

Posted: 21 Apr 2018 11:17 PM PDT

Hello community,

I am not a physicist by background but I like to learn. I have always been confused by the concept of fuel efficiency. How is it defined? On one side, I feel that it can be described as how many miles per gallon a vehicle can travel but then I get asked why isn't it the amount of horsepower or torque that can extracted from the fuel.

I can say "Hey Mazda is pretty fuel efficient as they can use 2.0 liter engine and give you 35 mpg" but what about "hey my Mitsubishi evo X can product 800 hp from a 2.0 liter engine" .

To me, they both hold fair arguments. However, I would to ask experts what fuel efficiency is? Is it defined as an equation of horsepower/torque or is it defined as an equation of distance traveled? Why?

Thanks

submitted by /u/SkynetGenisys
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How does a catalyst affect activation energy?

Posted: 21 Apr 2018 08:48 AM PDT

I have seen diagrams of catalysts which hold molecules in place so that they are in the correct orientation for reactions to occur but my textbook says that they provide a alternative route which lowers activation energy.

Does that mean orientation is factored into activation energy or are they separate things?

If so how do catalysts reduce activation energy? Does it do with the way they deform the electron shells of a molecule?

submitted by /u/PocketCharacter
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How often do collisions in LEO happen?

Posted: 21 Apr 2018 09:05 AM PDT

The humanity has been sending quite an amount of satellites, space shuttles etc. to the Earths orbit for the past ~60 years and from my understanding the LEO (Low Earth Orbit) is getting quite crowded by lost satellites, parts of shuttles and smaller debris.

My question is: How often do collisions between currently operational satellites and the ISS happen and how impactful are they?

As a side question, If we somehow created a device that could pull all the unwanted debris towards Earth to burn up in the atmosphere, how impactful would the emissions be on the Earth/would we even notice?

submitted by /u/TaZjec
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Why is majority of the world right-handed?

Posted: 21 Apr 2018 06:28 AM PDT

Just curious about this, there must be some explanation, right?

submitted by /u/Alsttr
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Why does the United States generally have a colder climate than most of Western Europe despite being at the same lattitude, and some parts even being further south?

Posted: 21 Apr 2018 01:48 AM PDT

Do bees have spatial memory when foraging for food?

Posted: 21 Apr 2018 01:33 AM PDT

Hi all

Background - ok my wife found a bumble bee looking docile in the house so she fed it some honey, the bee perked up and flew out of the house.

Now we've had what we think is the same bee fly into our house 3 days in a row and each time fly to same spot in the house where she fed the bee honey - presumably to look for the honey.

So my question is - do bees have memory of locations for food or is it entirely pheromone based?

EDIT: i'm surprised to not see a nature flair to add to this post.

submitted by /u/mitchanium
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