Questions tagged [biology]

Questions about biology are OFF TOPIC and should be asked on the Biology Stack Exchange. However, questions about biology in the context of physics (e.g., biophysics) can be on topic here if the primary concern is physics.

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Is possible to "isolate" some audio frequency? [closed]

I want to know if is possible to "isolate" some audio frequency for certain human that only this human can hear this "frequency spectrum", some animals can hear certain frequencies ...
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1 answer
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Can Low-Freq sound wave with High-Amplitude destroys human ear?

Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz. So that's mean human unable to hear 1 Hz frequency sounds since it's far under 20 Hz. At detectable frequency of human like ...
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1 vote
1 answer
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How do retinal cones see color when the cones pickup photons and not waves?

I am wondering how cones (photoreceptors in the retina) can see color if colors are wavelengths but cones send signals when they absorb photons. Maybe by using the energy level (or only being ...
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If we know information existed when life first began on earth, then can’t we surmise that information existed prior to earth life? [closed]

If true, then wouldn’t information have been created when the universe was created? In other words, if information existed from the start of the universe, then it’s possible that information can not ...
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-1 votes
1 answer
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Energy and force relation

So in simple machine we apple less force with more displacement to exert same energy as the load need so if energy is related to tiredness i.e. more energy you lose more tired you feel but by applying ...
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Wouldn't our own EM emissions be good the places to look for signs of intelligent life?

I read that only a narrow band of radio waves are reserved for astronomical observation, and humans emit all sorts of electromagnetic waves, which leads to my question: Could there be signals of ...
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Do photosynthesis and respiration violate the law of conservation of energy?

I don't know, if it's a physics question, biology or chemistry question but anyways here it is: I have been taught that for making one molecule of glucose in photosynthesis 18 ATP molecules are used ...
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At what rate does the human body heat itself?

The human body heats itself at some rate, because of this, I'm trying to add a forcing function to the differential equation known as Newtons law of cooling: $Q = hA(T-T_{env}) + f$, which I suspect ...
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15 votes
6 answers
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Would you run faster on Mars?

Given the 1/3rd of Earth's gravity on Mars and neglecting space suit limitations and also assuming you have maintained your muscle strength, would you run faster on Mars? The answer may not be so ...
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Chemical detector of radio waves?

Since there are molecules in the eye that can detect electromagnetic waves at light frequencies, would it be possible to detect radio waves (longer wavelength electromagnetic waves) biologically / ...
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0 votes
3 answers
91 views

Why can we hear instruments but not voices?

I've seen this graph: But I don't get something. Consider the 2kHz line (highlighted in red). This graph implies we can hear an orchestral instrument at 2kHz before we can hear a human at the same ...
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1 vote
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Is it actually possible to make an amputated hand move with electricity? [closed]

I was watching a TV show that involved the police tracking down an insane person who was using deceased limbs to perform experiments on. It then cuts to a scene where they find the safehouse with what ...
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3 votes
2 answers
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Does this work to reduce eyes strain? Enlarge the PC monitor with a lens

I have an idea to reduce eyes strain, but don't know if it works. I work by looking at PC monitor all day long and I believe my myopia condition is getting worse and eyes strain occurs are due to ...
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2 votes
3 answers
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Will I get a shock holding a superconductive wire?

Assume a current carrying superconductive wire is in front of me, with no voltage source attached. If I hold it, will I get a shock? Forget for a minute that the superconducting wire will be too cold ...
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2 votes
2 answers
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Where does the extra energy go when walking vs biking?

We burn a lot more Calories when walking a mile vs biking a mile. Why? Where does the extra energy burned from walking go? Is it that the mechanics cause the body to generate a lot more heat energy ...
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1 vote
2 answers
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How can work done by a person be negative, e.g. in lowering a book? [duplicate]

I am holding a book of mass 0.5 kg in my right hand at a height of 1 m from ground level. The book is lifted to a height of 1.5 m above ground and then brought down to its original height of 1 m. The ...
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Is my assumption for thinner limbs on race horses / hounds correct? [closed]

My assumption -as a layman- is that thinner limbs (given equal compared length on normal animal limbs) can accelerate faster due to their reduced mass i.e. unsprung weight transfer in regards to g-...
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1 vote
3 answers
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Will a body start to deform if it is accelerating very fast? [closed]

I had a question in my mind that when a body will start accelerating in outer space where there is vacuum and no other object to hit the accelerating one, then will that body start to deform? I mean ...
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-1 votes
2 answers
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Does sound travel through FINGERS?

as we know that sound's speed is fastest in solid (and slowest in air). QUESTION - what is the reason when we close our ears and don't really hear loud noises though sound travels faster in solids?
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What are some good resources to study Biophysics for an undergraduate level?

I am studying Biophysics as a part of my Biotechnology bachelor program. I want to study the subject as best as I could, from a beginner level to graduate level. Please, recommend textbooks, online ...
3 votes
3 answers
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What does it mean for sunlight to be of low entropy?

I once listened to a lecture by Sir Roger Penrose on life and also read the second answer to this question. If I understood correctly, then the reason why life still exists on earth inspite of the ...
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How can effect of electromagnetic radiation on human sperm be explained physically? [closed]

I am not sure if this question belongs here. If it doesn't belong here, feel free to remove it (and maybe tell me where to post this instead?). I have been researching the question of whether ...
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9 votes
5 answers
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How does the electrical ground rod work?

I was reading this article about shock current path, but it seems to be contradicting answers that I have seen on this site regarding electric shock. I can't find the original question but it was ...
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0 votes
1 answer
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Physical Model of Exercise

Trying to model caloric effects on the body when exercising. I think I have something for lifting weights, but at a loss for running or bicycling. Lifting Weights. I think this is pretty easy. ...
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4 answers
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Are Humans and DNA the only things capable of creating order (Negentropy)? [closed]

the 2nd thermodynamic law insists that our universe is reacting towards a maximized state of entropy (disorder). Yet it is clear that order exists in the universe with cosmological and biological ...
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45 votes
4 answers
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At which slope angle is a runner faster than a bicyclist?

On level terrain a bicyclist is faster than a runner. On a steep slope a runner is faster than a bicyclist. (That's why you see bicyclists pushing their bikes uphill.) Can we calculate the angle where ...
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0 votes
2 answers
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More on Bicycle Gears

I read a related post on bicycle gears and I still have a doubt. In low gear, the output force exerted on the ground is larger than the output force that would be produced in high gear. A large ...
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1 vote
2 answers
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What physics could be applied to accelerate a person from zero to 8000 m/s if you want to: a) Minimize the time, and b) Not kill or hospitalize them? [closed]

My thoughts on this are that you would: Immerse the person facing forwards in a neutral buoyancy fluid, Slew the acceleration up and down just enough to avoid shock waves in their body, Increase air ...
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1 vote
2 answers
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If I lift a body with a force greater than its weight, what will happen to the excess energy provided to the body

I will give an example to explain my question. Case 1: An elevator lifts body a with force equal to its weight for a distance $d$ Energy given to the body (work done)$=$ Weight $×$ $d$ Amount of ...
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1 vote
2 answers
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How to run faster? Velocity vs foot on floor

I was wondering how you can increase your running speed depending on how you set your foot on the floor. In other words, how does the position of the foot area on the floor influence the speed/...
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3 votes
2 answers
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What potential difference or current would kill a person?

I was watching this YouTube lecture, and earlier in the vid he mentions 120 volts from a power outlet would kill you. So if human resistance is $300\ \Omega$, $0.4 \rm A$ should be enough to do the ...
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1 vote
0 answers
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Is there any possible scenario where a human could directly sense gravitational waves (preferably without being destroyed)? [duplicate]

Merging black holes radiate enormous amounts of energy - several solar masses worth! Unlike most astrophysical happenings, this happens on very human timescales. Most of the energy is released in the ...
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8 votes
3 answers
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What happen if all the carbon-14 atoms in a person body decays at once?

What happens if all the carbon-14 atoms in a persons body decays at once? Would they die or will they be unaffected?
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6 votes
1 answer
361 views

Why does the length of a person change when they are lying down or standing up?

It's just an observation. I don't know if there is actually a physics theory behind it. I am looking for an intuitive answer.
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4 votes
1 answer
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What is the science behind Red light therapy? Infared and low spectrum EM waves sounds fancy to some but is it more than heat and a red light bulb

I have some scientific background and I own horses. So many therapies to alleviate pain in horses are available on the market that are not regulated by any scientific body. The benefit and the ...
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1 vote
1 answer
71 views

Would a human be able to descend to depths in the ocean that would crush their body?

Would not the same forces that would crush the body also resist descent? Or would the body be too buoyant to descend below the point at which the water would crush a human?
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2 answers
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How does the Extreme Heat of a Lightning Bolt not Kill Anyone?

Ok so, according to various different online sources, a single bolt of lightning is capable of raising the temperature of the air it rips through to... ummmmm... 50,000 degrees Fahrenheit? What? That'...
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2 votes
4 answers
76 views

Why do we get a shock from electric wire instantly? [duplicate]

As we know the drift velocity of electrons in conductors is very low and it is about a few millimetres per second. Now suppose I hold one end(naked) of a wire which is not connected to any source. ...
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0 votes
3 answers
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Convex lens in our Eyes

I just learned that our eyes are made up of bi-convex lens, and I know that convex lens are also called converging lens since they converge to form real images that can be caught on a screen. But why ...
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1 vote
3 answers
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Theoretically, could radio waves carry enough energy to destroy bacteria or viruses by resonance?

I've been reading recently about a mysterious and possibly hokey medical device of the 1930s. It was a variable-frequency radio emitter, invented by a Dr. Rife, which was supposed to kill various ...
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1 vote
1 answer
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Why objects dont appear closer and smaller to a myopic person and far and larger to hypermetropic person after wearing spects?

I am a myopic person, and wear a concave lens. It is taught to us that lens I wear help to form image on my far point and thus help me to see far object. 1.But we have also learn that concave lens ...
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-1 votes
1 answer
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What are the factors affecting the amount of blood refractive index? [closed]

I read an article normal blood refractive index is 1.35. So it's for everybody? I want simulate a sensor to detection flu virus using micro ring resonator then I find the wavelength shift 24 nm but my ...
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1 vote
2 answers
174 views

Which among alpha, beta and gamma emitters is most dangerous for human body?

Lets say we have three candies: One with alpha emitter in it, one with beta emitter in it and one with gamma emitter in it. All have similar activities. You must eat one, put one in your pocket and ...
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1 vote
0 answers
126 views

Can Consciousness be Understood as an Emergent Phenomenon of the Evolution of the Human Brain? [closed]

Straight question - is explaining (or at least understanding) consciousness in the realm of physics? Detailed question: We know that consciousness exists. Or rather, I know that I have it. The rest of ...
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3 votes
0 answers
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Why does bringing a helium filled latex balloon close to my ear make it feel pressurized?

Title pretty much says it all. Got my son some balloons for his 1st birthday. He was playing with them while I was holding him and everytime he brought one closed to my ear it made my ear feel ...
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Microwave effect

I'm new to the forum. I state that I am a technician and I have to deal every day, even with various types of radar, but I am not only concerned with this. I found out on the web about the danger of ...
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2 answers
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Can grounding wrist prevent electrical shock?

Today while repairing some electronics and wearing anti-static wristband like on picture below I got thinking - in theory, would it be possible to avoid shock while working on mains by grounding ...
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0 votes
1 answer
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Are there an infinite or finite number of colors (can we see infinity?) [closed]

Take any blue or red, mix in equal parts and you have purple. Now mix 50 units of red and add 25 units of blue for another purple, then 50 units of red and 12.5 units of blue for yet another purple ...
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1 vote
1 answer
118 views

Could you make someone magnetic without killing them? [closed]

Edit: having read some (very helpful) responses, I now think my question is closer to this: Could you, either by somehow distributing a foreign substance throughout someone's body, or by somehow ...
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1 vote
1 answer
104 views

Why did mirror-image life not evolve? [duplicate]

Mirror life is a hypothetical form of life with mirror-reflected molecular building blocks. For instance, a mirror virus RNA would be constructed with left-handed sugars. Why do we see absolutely no ...
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