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Sunday, February 17, 2019

Theoretically the efficiency of a solar panel can’t pass 31 % of output power, why ??

Theoretically the efficiency of a solar panel can’t pass 31 % of output power, why ??

Theoretically the efficiency of a solar panel can’t pass 31 % of output power, why ??

Posted: 17 Feb 2019 06:06 AM PST

An information i know is that with today's science we only reached an efficiency of 26.6 %.

submitted by /u/Spirou27
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Theoretically, if a rocket ship kept constant thrust on in space with unlimited fuel, will it keep accelerating indefinitely?

Posted: 17 Feb 2019 01:33 AM PST

Why do delocalised electrons result in a more stable compound?

Posted: 17 Feb 2019 06:36 AM PST

For example, comparing cyclohexa-1,3,5-triene and the structure of Benzene, due to the delocalised ring of electrons in benzene, it is more stable. Why is this the case?

submitted by /u/AhmarIT
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Why does the moon have so many impact craters compared to the Earth?

Posted: 16 Feb 2019 09:42 PM PST

Does gathering information about a thermodynamic system decrease its thermodynamic entropy?

Posted: 16 Feb 2019 11:28 PM PST

If you have an ideal gas in a chamber, and you have the ability to see individual particles, can you extract useful work out of it? If I know that a certain particle has a higher than average kinetic energy, theoretically I can extract useful work out of that particle using Szilard's 1 particle engine, can I not? Thus, getting that information reduce the entropy of that chamber because I can get useful work out of it.

Does this mean that the thermodynamic entropy got converted to information entropy? It may increase the thermodynamic entropy of the memory unit that is holding that data, to keep with the 2nd law. Is there a problem in this logic? Thanks!

submitted by /u/x0Dst
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What causes the "fear" of water during rabies?

Posted: 16 Feb 2019 11:14 AM PST

I often try to figure this out with the internet they all say that it causes convulsions in the throat but I always wondered why, what causes the human body to convulse with rabies, I never got a clear answer

submitted by /u/Moonpillars
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How do an insect’s antennae joints work? I’ve seen the joints on an ant’s antennae from a microscope and they seem to be a simple ball. How do they move around?

Posted: 16 Feb 2019 07:46 AM PST

Wouldn't a gamma ray be able to knock electrons out of the nucleus in silicium?

Posted: 16 Feb 2019 05:13 PM PST

I've read that silicium is used in solar panels because solar rays can knock their electrons out the nucleus, and because gamma rays are stronger than solar rays and can travel really far shouldn't they also knock them out?

submitted by /u/nigma1337
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What are the major restrictions of cold fusion? Is there any chance of it happening, and how?

Posted: 16 Feb 2019 09:03 PM PST

I'm on a small to mid-sized boat, far from any coast, and a tsunami is heading in my direction. What happens? Do I notice anything wrong?

Posted: 16 Feb 2019 07:13 AM PST

How exactly does mechanical energy translate to calories burned?

Posted: 16 Feb 2019 09:57 AM PST

Say I lift a 25kg weight from the floor to my chest (about 1.5m) -- around 370 joules of potential energy. If a calorie is roughly 4.2 J, does this mean I just burned a little under 90 calories?

If not, how does mechanical energy like this translate into how calories are burned? That seems like a lot of calories, but I'm not sure where else the energy would come from. Or, are there different definitions of calories?

submitted by /u/eyebrowgamestrong
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Does high/low frequencies play a role in how much heating damage is done from loud music?

Posted: 16 Feb 2019 07:50 AM PST

I'm curious whether one person standing in front of a higher frequency speaker would end up more 'ear shot' the next day, compared to someone standing in front of a bass speaker.

Lower frequencies like bass and sub-bass have longer wave lengths and can be felt by the vibrations they cause. On the other hand high frequencies can't be felt, they have shorter wave lengths, thus leading me to believe they're the culprit for the 'shot ears' and hearing loss at concerts.

submitted by /u/Meg--Griffin
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When will a horizontally-hung rope break under its own weight?

Posted: 16 Feb 2019 10:38 AM PST

For example, say I tied two ends of a long rope to the top of two radio towers (of equal height), how far apart could these towers be before the rope would break from its own weight? I've tried to look into this before, all answers seem to be for a vertically-hung rope.

submitted by /u/mrlugg22
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How did the Megalodons go extinct, and if evolution made them into sharks why are they so small?

Posted: 16 Feb 2019 08:53 AM PST
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Saturday, February 16, 2019

How does the excess salt from salting roads affect the environment? Things such as bodies of water or soil quality?

How does the excess salt from salting roads affect the environment? Things such as bodies of water or soil quality?

How does the excess salt from salting roads affect the environment? Things such as bodies of water or soil quality?

Posted: 15 Feb 2019 05:03 PM PST

If for some reason you have a handful of feces in your hand and you wash it off with disinfectant soap but your hand still smells like feces, does that mean your hand is still contaminated?

Posted: 15 Feb 2019 08:51 AM PST

How are potholes created?

Posted: 16 Feb 2019 02:59 AM PST

I'm talking about dead vertical potholes on asphalt that look like someone brought a jackhammer and made an almost perfectly round pothole. The ground around them looks in good condition and unaffected. What causes this to happen in a small part of the road and not the rest?

submitted by /u/savvaspc
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How do octopi kill sharks? Do they "drown"/suffocate them? Do they snap their bones?

Posted: 16 Feb 2019 06:22 AM PST

Saw a video on this and it's pretty crazy, but I am curious about the mechanism of how the shark actually dies.

submitted by /u/thank_you_next
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Trans fat reduction: Are we healthier now?

Posted: 15 Feb 2019 08:29 PM PST

Dr. Walter Willett of the T.H. Chan School of Public Health at Harvard has been widely quoted as estimating that industrial trans fat elimination will prevent 90,000 deaths annually. Now that most of that has taken place, have reduced rates of coronary disease and associated deaths over the last few years shown up statistically? Or is it too early to know?

submitted by /u/Kukisvoomchor
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Why is it that when your hand is shaky, you can easily read what you're holding while others would struggle to follow it with their eyes?

Posted: 16 Feb 2019 04:37 AM PST

I hope the flair is correct.

submitted by /u/SinanDira
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What differentiates the vocal cords of someone who can sing high and someone who sings low? And what about both?

Posted: 16 Feb 2019 04:02 AM PST

Why can’t we combine all of the vaccines into one big super vaccine and give it to babies at a young age instead of going through different rounds of vaccines at different ages?

Posted: 15 Feb 2019 06:03 PM PST

How often do wild animals get cancer?

Posted: 16 Feb 2019 02:06 AM PST

I have never heard of wild animals suffering from cancer, is there any documentation about this or reports that I have missed?

I am wondering if there is any link between cancer and human society/activity (food, manufacturing, machinery, etc) because so far I have only heard of pets, animals with close contact to humans, ever getting cancer.

Thank you :)

submitted by /u/ScheduledTiger
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Why are some prions considered to be protease-resistant?

Posted: 16 Feb 2019 04:05 AM PST

I've tried searching around about what makes prions structure resistant to proteolysis, but I've come up with nothing. It would be appreciated if someone could explain to me how this change in secondary (higher percentage of beta sheets in disease causing prions) and tertiary structure makes a prion resistant to proteasomes.

submitted by /u/Girimehkala
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How realistic is in movies when they close dead people's eyelids? Aren't eyelids supposed to be stiff like the rest of the body? How much pressure must be applied? Are they prone to reopening?

Posted: 16 Feb 2019 01:43 AM PST

With all these new cases of measles, if the virus mutates, can people who have already been vaccinated become susceptible?

Posted: 16 Feb 2019 01:20 AM PST

With every case of measles, the chance of mutation exists. I know that every virus has a different mutation rate, how high is measles compared to other diseases like chickenpox? When the new cases pop up, do they test that strain against the one used to make the vaccine? How exact do the antibodies given in the vaccine need to match to be effective?

I have a 10 month old child and have been diligent in getting her vaccines and her MMR is due soon. Since she is still vulnerable, and we live in Las Vegas where visitors from all over the country and world come to spend money, I have been alarmed at the outbreaks and the possible consequences.

submitted by /u/sharp_tooth01
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Are there any substances the Liver or Kidneys can't remove? Therefore in our blood forever.

Posted: 16 Feb 2019 02:38 AM PST

What is the biological mechanism that caused malformations in inbreeding?

Posted: 16 Feb 2019 02:33 AM PST

Why is it that humans have a tendency to have birth defects?

Why can some animals, like the cheetah, circumvent this mechanism?

submitted by /u/SatanicOnion
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What happens to addiction when You are in coma?

Posted: 15 Feb 2019 08:49 PM PST

When people for example addicted to nicotine, wake up from a coma, are they still addicted or can they immedietly quit? What about stronger addictions like heroine? Does doctors give special medications to addicts when they are still in coma?

submitted by /u/iwuspl
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How do severe allergic reactions work? How and why can someone die from eating something that is innocuous to most others?

Posted: 15 Feb 2019 03:54 PM PST

How do our lungs get rid of particulate? Like smoke and sawdust and tiny foreign matter?

Posted: 15 Feb 2019 06:33 PM PST

I breathe an incredible amount of horrible things at my job. I wear a respirator when I am doing something really hazardous, but there is always a haze of dust in the air made of plastics, adhesives, paint, lacquer, ink, wood, and things like plywood and mdf.

edit: and aluminum, lots of aluminum dust in the air.

submitted by /u/xlitawit
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Why do we ice swelling injuries when the swelling is a natural bodily reaction to the injury?

Posted: 16 Feb 2019 01:30 AM PST

Why does stress weaken the immune system?

Posted: 16 Feb 2019 03:34 AM PST

When calcium carbonate is put in distilled water, will it cause the increase of pH of the water solution?

Posted: 16 Feb 2019 06:34 AM PST

We had a discussion at lunch with my friends yesterday. Calcium Carbonate in water.

​

Ok, as far as I know calcium carbonate is preeetty insoluble in destilled water, especially at pH 7.4. But Here is the question, if put in slightly acidic pH (6.0, lets say) will it increase the pH of the surrounding medium or will that stay the same?

​

A penny for your thoughts.

submitted by /u/Pharmaki
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Why does blue light look so much darker than red or green light that is said to have the same intensity?

Posted: 16 Feb 2019 06:30 AM PST

"Intensity" here meaning brightness/saturation of light as given by, for example, a Web hex color value. Why does Web color #0000FF look so dim compared to #FF0000?

submitted by /u/A_Mirabeau_702
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Is there any way of knowing what was the supposed lifespan of dinosaurs?

Posted: 15 Feb 2019 09:29 PM PST

I mean if they didn't get hunted down or got killed by a rock falling to their heads. Do we know if Argentinosaurus lived to be hundred ? What about Spinosaurus, did they die at the ripe old age of 34?

submitted by /u/Wectium
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What is/are the preferred voting method/s present when trying to rank entries such that the final ranking is representative of the overall vote?

Posted: 15 Feb 2019 11:42 PM PST

You can also assume that each of the entries can be given a score by the voters; like say 88/100 or something like that. Obviously, I don't require that the answer be weighted but I would love to see the reasoning behind why a weighted voting method would not work out well in this scenario over a non-weighted one; if that were to be the case. The number of voters is not that large, assume 6<n<12 wherein n stands for the number of voters. Also, the method I'm looking for should also try to minimize tactical voting as much as possible so that when one voter gives an entry a low score in a blatant effort to tank that entry's standing in the final ranking, the effect of the tactical vote is minimized. I've tried to search literature but some complicated terms come up, and as a layman with regards to this field, I would definitely love some help on this area of mathematics and/or statistics.

submitted by /u/Raging_SEAn
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Friday, February 15, 2019

Why are some viral infections permanent, but some are cleared up within a few days? What determines how long it takes the body to clear the infection?

Why are some viral infections permanent, but some are cleared up within a few days? What determines how long it takes the body to clear the infection?

Why are some viral infections permanent, but some are cleared up within a few days? What determines how long it takes the body to clear the infection?

Posted: 14 Feb 2019 06:30 PM PST

When a gas gets compressed the temperature increases. According to Google the temperature of a black hole is near absolute zero. If a gas gets compresed enough that it becomes a black hole, in wich step does it loose that temperature?

Posted: 15 Feb 2019 03:01 AM PST

Does “wind chill” have any effect on ice formation or retention? In other words, if the actual temperature is 33F, but the wind chill is 18, will ice last longer than a temp of 33 with a “real feel” of 36?

Posted: 15 Feb 2019 04:54 AM PST

In other words, is wind chill just something to help make weather reports more sensational, or is there any actual physical effect?

submitted by /u/ericdavis1240214
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When did physicists realize that nothing can move faster than light and that the speed of light is immutable regardless of the inertial frame?

Posted: 15 Feb 2019 05:25 AM PST

After watching this video on Sixty Symbols, I understand that mathematically by applying the Lorentz Transformation to calculate the speed of the photons coming out of a torch from a passenger on a passing train for an observer's frame of reference outside the train, one obtains c as the result for both observers. However it's not clear to me if this is a consequence of Einstein's special relativity, or if the immutability of the speed of light had been previously established.

I wildly guess then, without knowing much about the Maxwell Equations that it was those which established the speed of light as constant and the maximum achievable in the universe, but I wonder how and would be thankful if someone could point me to where I can find more information about this.

​

Thank you!

submitted by /u/Javihache
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Does a concentration gradient only refer to a single unique substance?

Posted: 15 Feb 2019 08:05 AM PST

Let's say I have a membrane with 1 mol/L Mg2+ on one side and the same concentration of Ca2+ on the other;

Does this count as a single concentration gradient 1:1

or as two 1:0 and 0:1 ?

If the second possibility is correct my follow up question would be:

What is the property that governs what each substance is? Is it charge? Size of the nucleus?

How does the universe know this?

Thank you!

submitted by /u/MrSebu
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How does alcohol work as a muscle relaxant? Are there any other substances that have the same effect?

Posted: 15 Feb 2019 06:26 AM PST

I was wondering how alcohol affects the body and if there was some way to achieve the same relaxing effect on the muscles as alcohol without impairing cognitive function, like coordination or judgement.

submitted by /u/Puckosar
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The solar system is one of many in the Milky Way, which is one of 54 galaxies in our local group. That local group is part of an even bigger structure. Is there a limit to how large these structures can be, or will we keep discovering larger and larger ones?

Posted: 14 Feb 2019 09:32 PM PST

How are antimicrobial agents tested? For example, if scientists wanted to test the antimicrobial properties of Lysol, how would it be tested?

Posted: 14 Feb 2019 11:15 PM PST

I'm talking about household disinfectants, something that would be used in a household setting for perhaps disinfecting the bathroom or kitchen counter, not testing antibiotics against an extremely specific type of microbe. Would the testing be done so that the product being tested is directly applied to a surface, allowed to take effect, then swabbed for microbes and then placed into a Petri dish, then placed into an incubator, and then observe for microbes on the agar? Or would they swab the surface first, grow some colonies of the bacteria/whatever else is on there, then drop a small, sterile disc of filter paper soaked in the antimicrobial solution and then placed back into the incubator and then observe how much of the growths in the Petri dish have been killed off? What is there are large colonies of microbes growing? That's not exactly a real-life representation of a common household surface in need of some disinfecting. Any links to a detailed procedure lab? All feedback is appreciated!

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(edit: spelling)

submitted by /u/WhatEvenIsPalmer
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When sick, what causes fever?

Posted: 15 Feb 2019 07:55 AM PST

How long does the collapsing phase of a supernova last?

Posted: 14 Feb 2019 09:03 PM PST

Supernova's occur when a large dying star collapses on itself and then explodes. Given the cosmic scales involved I'm sure this collapse is not instantaneous, how long is all the matter in a dying star collapsing before it explodes?

submitted by /u/InfiniteTrain
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Is it probable that the solar panels from the Mars rover get cleaned by a storm or anything else?

Posted: 14 Feb 2019 05:09 PM PST

Has the Earth expanded over the last 3 billion years and is it still?

Posted: 15 Feb 2019 05:31 AM PST

I know about the Rutherford-Geiger–Marsden experiment, shooting particles through gold foil, etc., but how did they know how many particles they fired?

Posted: 14 Feb 2019 04:46 PM PST

Do all species of mammals produce identical twins?

Posted: 14 Feb 2019 11:01 PM PST

Given that mass x gravity = weight, if I were in a 0 gravity environment and I lifted an otherwise heavy car, would I need an extraordinary strength or not?

Posted: 15 Feb 2019 04:16 AM PST

The question came up in the comments of a certain anime and I am confused by some people assuring that you need strength to lift it anyway. As far as I know, you shouldn't need it.

submitted by /u/MacaCabral99
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How much DNA do scandinavians share with the germanic tribes who migrated there, compared to the earliest populations?

Posted: 15 Feb 2019 03:20 AM PST

Samis not included

submitted by /u/rogne
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How did Blackett and Runcorn determine that Earth's magnetic poles had drifted or flipped?

Posted: 15 Feb 2019 01:20 AM PST

I'm reading "A Short History of Nearly Everything". In it, Bill Bryson tells how Patrick Blackett and S. K. Runcorn determined by the use of tiny grains of iron in ancient rocks, where the poles had been during the creation of said rocks.

I told my father this neat fact and he said: "How do they know the rocks weren't just flipped instead of the poles?".

How did they?

I know how magnetic tape works and thought it could be similar to the alignment of the particles embedded in the tape that represent the waveforms, but as I am no geologist, could not answer his question.

submitted by /u/morsmordre-
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Why does liquid metal that solidifed quickly has a high strength?

Posted: 15 Feb 2019 01:07 AM PST

Could we use the color of a planets aurora to determine the sustainably of human life?

Posted: 14 Feb 2019 09:07 PM PST

Is it possible to express a musical sound's timbre quantitatively?

Posted: 15 Feb 2019 12:51 AM PST

I know there are a thousand things that could affect tone, and you would probably be quite limited if you were to express it in a single number but, I think it would be super interesting to be able to experiment with different aspects of an instrument and be able to measure their effect on tone.

Even if you couldn't express the whole tone as a single number (which I don't really expect is possible), are there any major aspects of tone that could be expressed as a number?

submitted by /u/ALackOfIntelligence
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