The biophysics tag has no wiki summary.
35
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7answers
1k views
Cyclist's electrical tingling under power lines
It's been happening to me for years. I finally decided to ask users who are better with "practical physics" when I was told that my experience – that I am going to describe momentarily – prove that I ...
21
votes
7answers
3k views
Why does holding something up cost energy while no work is being done?
I read the definition of work as
$$W ~=~ \vec{F} \cdot \vec{d}$$
$$\text{ Work = (Force) $\cdot$ (Distance)}.$$
If a book is there on the table, no work is done as no distance is covered. If I ...
18
votes
1answer
571 views
Why can Hiroshima be inhabited when Chernobyl cannot?
In Hiroshima, atomic bomb was dropped, but today, there are residents in Hiroshima. However, in Chernobyl, there is no resident living today (or very few). What made the difference?
16
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2answers
742 views
Why can't Humans run any faster?
If you wanted to at least semi-realistically model the key components of Human running, what are the factors that determine the top running speed of an individual? The primary things to consider would ...
14
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2answers
2k views
How does space affect the human body (no space suit, no space craft)
How does "outer space" affect the human body? Some movies show it as the body exploding, imploding or even freezing solid.
I know space is essentially a vacuum with 0 pressure and the dispersion of ...
13
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4answers
2k views
What does Peter Parkers formula represent?
Okay, so the trailer for the new Spider Man movie is out and appearently our friendly physicist from the neightborhood came up with something. However I can't find out what this is.
...
12
votes
1answer
382 views
Is colour, as represented using primary colours, accurate only to humans?
Slightly biological, hopefully physical enough to be answered.
Suppose a magenta hue is represented by a mix of red and blue pigment. This is all very well for a creature with red and blue ...
10
votes
5answers
594 views
Octave equivalence: biological or more?
I'm a graduate student in mathematics doing a bit of research in signal processing and Fourier analysis and I've come across a question that could probably be better answered by a physicist:
Is the ...
8
votes
5answers
886 views
What happens to light after it enters an eye
What happens to the light [energy] after it enters an eye and hits the rods and cones? I presume the energy becomes electrical, and it must be near 100% perfect, else our eyes would heat up? Or am I ...
7
votes
1answer
196 views
How can tunneling be one-way?
I was recently at a lecture given by Dr. Harry Gray, a biophysical chemist, where he talked about how proteins (specifically those involved in photosynthesis) are able to use various phenomena, like ...
7
votes
3answers
678 views
What's the source of electricity for the human brain?
I keep hearing that there's always electrical activity taking place inside the human brain. Our heart and various other organs function because it receives electrical signals called impulse. But, ...
6
votes
2answers
548 views
What physical forces pull/press water upwards in vegetation?
Each spring enormous amounts of water rise up in trees and other vegetation. What causes this stream upwards?
Edit: I was under the impression that capillary action is a key factor: the original ...
6
votes
3answers
448 views
Do eyeballs exhibit chromatic aberration?
Fairly straightforward question. If not, why not?
I suspect that if they do, it is not perceived due to the regions of highest dispersion being in one's region of lowest visual acuity.
6
votes
2answers
928 views
How are the calories in food calculated?
This is intended to be a fun question. Calorimetry used for calculating the heat generated from chemical changes has been around for centuries, however, I suspect the process for calculating food ...
6
votes
2answers
367 views
Quantum Computing and Animal Navigation
Someone sent me this link to a talk by Prof. Klaus Schulten from the University of Illinois: (my emphasis)
Quantum Computing and Animal Navigation
Quantum computing is all the rage nowadays. ...
6
votes
1answer
697 views
What are the characteristics of the magnetic field surrounding a human brain?
The human brain is said to produce a magnetic field resulting from the action potentials released inside the brain. What's the nature of such a field in terms of size and strength, and what is the ...
6
votes
2answers
930 views
Are regular light bulbs better for the eyes than CFLs or “tube lights”?
I've heard that regular light bulbs with a filament are better for the eyes. Is the spectrum of one worse than the other? If so, are there any regulations for their use in industrial settings for ...
6
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0answers
197 views
Predicting the ratio of translational diffusion coefficients for a sphere and a sheet
Imagine that I have a spherical particle of molecular weight $M$, volume $V$, and some experimentally observed center-of-mobility translational diffusion coefficient $D_{sphere}$ in water. I take ...
5
votes
2answers
172 views
Effects of a very large magnetic field on the human body
Ever since reading about the NHMFL I have always wondered about this and asked several people without getting a good satisfactory answer. My question is, considering the simplest case let's say a ...
5
votes
1answer
1k views
Adverse Health Effects of Strong Radio Waves
A while ago, I was hiking near the Hollywood Sign in Los Angeles. When I got to the sign, I found out it was fenced off; with several signs and a security camera promising prompt enforcement. As I was ...
5
votes
1answer
2k views
Newton's color Disk
How does Newton's color disk work?
Newton's disk - Take a circular white color disk, make 7 equal intersections and paint section with respective VIBGYOR colors, now when you spin the disk in certain ...
4
votes
2answers
1k views
How can an an ant lift 50 times its own weight and pull 30 times its weight?
According to many sites like this one, an ant can apparently lift 50 times its own weight and pull 30 times its weight. Is it true?
Can it be proved using physics? Though most sites agree that an ...
4
votes
1answer
130 views
Radiation exposure to a child who was briefly in the presence of an adult who had received a 18FDG PET scan
I am a physician who thought she was good at math, but apparently am not as I cannot figure out this mathematical/physics question. (My background is obviously NOT nuclear medicine!) A family friend ...
4
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2answers
192 views
Why don't massive water-borne animals crush under their own weight when they're in water?
If you take a giant whale out of the water and put it on land for long enough, it will crush itself under its own weight. Why doesn't the animal get crushed under its own weight when it's in water?
4
votes
2answers
979 views
How efficient is the human body?
This question sort of comes to mind when hearing how efficient an internal combustion engine is turning chemical energy in mechanical energy (something like 20-40%) with lots of excess heat. As an ...
4
votes
2answers
98 views
Do viruses suffer from quantum de-localization?
Consider some microscopic life form. It should obviously be localized in space, in the quantum-mechanical sense, if it is treated as a single particle (though it is composite). If its characteristic ...
4
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1answer
278 views
How do sunflowers rotate?
Is there a physics mechanism to explain how sunflowers rotate to always face the sun?
I tried to find more information or references using google search, but no luck.
4
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2answers
374 views
Examples of circuitry using proton currents
Proton cuircuits and proton motive force are part of standard discussion in biology and processes involving photosynthesis. The sort of proton currents discussed in biology are obviously slightly ...
4
votes
1answer
46 views
What is the minimum pressure difference for your ears to pop?
I'm assuming the answer to this largely varies from person to person. Assuming you could instantly change the pressure around your head by amount $\Delta p$, what is the minimum $\Delta p$ for your ...
4
votes
1answer
169 views
Voltage drop over a cell membrane
Again, a problem from exam preparation:
[A] cell's membrane allows sodium ions to pass through it, but not chlorine ions. The cell is placed in a salty solution with a ten times higher ...
4
votes
8answers
569 views
Is relativity necessary for the existence of life?
If the universe didn't have the relativity principle, would it be able to support life?
Life consists of very complicated organisms. The operation of these organisms depends on the laws of physics.
...
4
votes
2answers
546 views
A quantitative explanation of EM coherence domains in liquid with DNA
I've been looking with interest at a recent biology paper claiming that DNA molecules give off electromagnetic signals which can cause the same types of molecules to be reconstructed at a remote ...
3
votes
2answers
334 views
Human perception of distance
When we see things around us, distant objects look smaller to our eyes than nearby objects do.
Is there any physics-related reason why our eyes or brain perceive things like this?
Or if this is ...
3
votes
1answer
340 views
How does a speaker produced different sounds?
What I have read is that a speaker produce sound by just moving a coil attached to a cone which moves back and forth. So, If I try to move the coil by hand, would it produce sound? If not why not? or ...
3
votes
2answers
257 views
How do animal perceive distances with their eyes and ears
I am studying how animals (including the human beings) can perceive distances thanks to their eyes and their ears. I am focusing on the fact that they always go in pairs: two eyes, two ears, etc.
...
3
votes
1answer
388 views
How does a stronger magnet affect the MRI image quality?
In which ways is a stronger magnet better for magnetic resonance imaging? I read that:
The field strength of the magnet will influence the quality of the MR image regarding chemical shift ...
3
votes
1answer
116 views
Why do beverages taste different based on how cold they are? [closed]
Why does temperature effect the taste of beverages?
Specifically, how does the temperature for example mask certain tastes ie filtered vs unfiltered water taste very similar at colder temp and Is ...
2
votes
4answers
1k views
Is it only red, green and blue that can make up any color through additive mixture?
I'm reading about color vision and have some trouble understanding the motivation for why the trichromatic theory was suggested in the first place. The book I'm reading ("Psychgology: The science of ...
2
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2answers
700 views
Why can you see a light in the location that the light source just left?
This is my first question on this site so forgive me for the awkward wording of the question. Basically, my question is why does light from, say, a sparkler, seem to remain where it just came from to ...
2
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2answers
102 views
Is metabolic rate the amount of heat given off?
The Basal Metabolic Rate is intuitively expressed as "the amount of energy you consume just sitting around." In some places it seems to be equated with the amount of heat that you give off.
Is this ...
2
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2answers
109 views
How Safe Are Heat Ray Guns?
Could a little meddling with the frequencies of the Heat Ray Gun beam result in frying crowds rather than dispersing them?
2
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2answers
155 views
Can wireless power transfer harm organic life by anyway?
Now, humanity can beam 50-60 watts power through 10 centimeter-thick concrete block. Can such wireless power transfer harm us by anyways?
2
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1answer
254 views
Entropy of a polymer contained in a sphere with infinitely thin chords
Imagine that I have a polymer (approximated as a freely diffusing, freely jointed chain with some number of subunits 'N'), and I place this polymer into a sphere of some volume 'V'. Next, I proceed to ...
2
votes
2answers
124 views
Computing microstate probabilities based on Boltzmann distribution for chemical systems - Is it rigorous?
One approach to predicting the folded structure of a polymer (DNA, RNA, protein) is to compute the probability that any particular part of the polymer $x_i$ is "paired" with another part of the ...
2
votes
1answer
160 views
Examples of piecewise smooth dynamical systems [closed]
I have recently been studying continuous dynamical systems whose phase space can be divided into a number of regions. Inside each of these the flow is smooth, but there is a discrete jump in the flow ...
2
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1answer
748 views
How to calculate calorie expidenture from lifting a weight?
Am I correct to say that when a human lifts a dumbbell from, say, 2 feet off the ground to 6 feet off the ground, he will have increased the potential energy of the weight and thus will have burned ...
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2answers
221 views
What happens to body chemistry at the speed of light?
Assume that I'm traveling at the speed of light in one direction. My brain is also traveling at the speed of light in that direction. Presumably there is at least one receptor site in my brain that is ...
1
vote
2answers
68 views
Was the early Earth radioactive?
I've been reading of the (surprising) fact we are uncertain on whether there is nuclear fission in the center of the Earth or not (yet we know so much detail on structures at the other end of the ...
1
vote
2answers
125 views
How much time can I power my laptop by eating one dessert?
Random question that popped into my mind after a 4-hours power outage. Let us assume that I am eating an extra dessert (250 kcal) and that I am using a bike and a generator to power my laptop (it ...
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2answers
215 views
Running: Determine how much more energy is needed per extra kilogram of weight
(I recently asked this on maths but was directed here)
I have recently become a runner and having a keen interest in kinematics I'm very interested in the maths/physics of my running.
Can someone ...
