The use of methods from the physical sciences to aid in the study of biological systems. Note that biophysics questions are only allowed if they are mainly about physics.

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1answer
156 views

Walking & Swinging

How can I show that the most convenient way to move the arms while walking is swinging them back and forth, alternatively? To pose the question in another way: can I prove, starting from the ...
3
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0answers
113 views

Fluctuation spectrum of lipid bilayer membranes

I am interestend in calculating the fluctuation spectrum of a thermally fluctuating 2d membane which is only subject to a surface tension $\sigma$. ($\mathcal{H}=\sigma\int\mathrm{d}A$) Depending in ...
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2answers
2k views

Is plant photosynthesis more efficient than solar panels?

Is photosynthesis more efficient than solar panels? If so, by how much?
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2answers
770 views

Frequency of touch, taste, and scent [closed]

So I was thinking about sound - and how anything below 20Hz is basically inaudible to humans (because it is too low of a frequency to be recognized), as well as anything above around 20KHz (because it ...
2
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3answers
373 views

Electric impluses inside nerve cells

I'm not a biologist, nor physicist, but there is one thing I try to understand about the elecricity inside human body. I wasn't sure whether place this question here, or perhaps on biology portal, but ...
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0answers
17 views

Seeking help on simplified mathematical (biophysical) model of serpentine locomotion in viscoelastic environment

I'm trying to build a mathematical model of C. elegans locomotion under overdamped viscous environment. In order to simplify this problem, I use six discrete pieces of rigid cylinders to represent ...
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3answers
2k views

How do birds generate thrust?

I have been watching this video carefully and I want to know how the wings of birds generate thrust. This is because the wings are more or less flapping up and down --- generating the lift. But I do ...
2
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2answers
159 views

Order of magnitude estimation for some intriguing questions

The physics TA showed us a few examples in which one can estimate many things from first principles, sound logic, and scaling arguments. This led usually to understanding of why some numbers have the ...
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0answers
66 views

Medical/Physics Question - Cut Off Finger Preservation

This question might require some knowledge of medical/tissue, but physicists seem to know everything, so figured I've give it a shot here ;) When people put cut off fingers they are told to put the ...
3
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1answer
144 views

How accurately can we measure human electromagnetic fields?

How accurately can our current technological tools measure the human bio-electromagnetic field emitted by a person? Or, to put it differently, does each person have a different electromagnetic field ...
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2answers
98 views

“In-head” sound intensity with and without earplugs

When you bite something in two pieces, e.g. a piece of hard candy, you hear the sound through two sources: vibrations in the air, entering your ears from the outside and internal vibrations in your ...
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1answer
365 views

Measuring energy when no work is done — comparing push-ups to planks

tl;dr Is there any meaningful (physical) way to compare the energy expended in the exercise of doing $x$ pushups in $t_1$ seconds, vs the exercise of doing the plank for $t_2$ seconds? I'm ...
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2answers
195 views

While holding an object, no work done but costs energy (in response to a similar question)

I read the answer to Why does holding something up cost energy while no work is being done? and wanting to know more, I asked my teacher about it without telling him what I read here. Instead of ...
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0answers
70 views

Which body position causes the least amount of negative acceleration? [closed]

Let's say you are in the air 500 meters above flat land and you have no parachute. Which pose - forming a sphere or spreading all extremities to make yourself as wide as possible or other - is the ...
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0answers
45 views

Would a $50\: \mathrm{Hz}$ spinning magnetic plate in front of a human generate harmful current?

We know that spinning magnetic plate will generate current inside any wire. so if we stand before 50Hz spinning magnetic plate, then, does that 50Hz spinning magnetic plate in front of us (human body ...
2
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1answer
85 views

Why electric field has a major role in vision?

Although the electromagnetic wave is made op of both electric and magnetic fields the electric field contributes much in vision and is thus, called the light vector. But, why is it that the electric ...
2
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1answer
124 views

Can there be some non-electromagnetic radiation which would be perceived by human eye as light?

Can there be some non-electromagnetic radiation which would be perceived by human eye as light? I mean, say ultra-sound or some particle rays etc.
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1answer
178 views

Does the space between molecules have no pressure?

In any living organism there exists are space between cells filled with interstitial fluid. Loss of this fluid into abnormal areas (3rd spacing) can cause relative to severe hypo-volemia. The fluid ...
2
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1answer
152 views

physically modelling the Saltatory nerve impulse transmission?

The nerve impulse transmission is specifically a biophysical process. Under a resting stage, the membrane is already polarised (presence of charge on either side leading to a potential difference ...
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3answers
4k views

How does blood/saliva boil in outer space?

Why would the blood boil? Is it because of the temperature or pressure? Because I really can't figure it out. I thought space didn't have a temperature above freezing unless close to a star or the ...
2
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1answer
307 views

Would there be EMF induced in our body due to electromagnetic radiations?

The experiments of innovative Faraday and Joseph Henry in USA, conducted around 1830, demonstrated conclusively that electric currents were induced in closed coils when subjected to changing magnetic ...
9
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1answer
704 views

How much does increased world population contribute to global warming?

In 1974 there where 4 billion people on earth. Now in 2013 we passed 7 billion people. So the world population is nearly doubled in 40 years. Every living human being also haves a body temperature of ...
6
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1answer
519 views

Do human bodies give off a consistent but unique radiation/electromagnetic/energy signature?

Is there any facet of the energy emitted by a human body that is consistent and unique - like a fingerprint, but a signal that could be detected by a remote device?
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2answers
221 views

Difference in perception of unpolarized and polarized light

What is the difference in perception of polarized light and unpolarized light? What difference does polarized light cause to our eyes?
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2answers
4k views

How do stun guns not kill people?

Now, I've seen a lot of answers to this sort of question, but most of them provide answers that don't actually make sense from a physics perspective. As an example of such an answer, I've commonly ...
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2answers
331 views

Is two cars colliding at 25 mph the same as one car colliding into a wall at 50 mph in reference to injuries?

This question has been asked using 50 & 100 mph reference, see this Phys.SE post and links therein. However, I am interested in the potential injuries to occupants of the autos. As the one going ...
0
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1answer
637 views

Calories burned doing 1 squat [closed]

To calculate the calories burned doing 1 squat, wouldn't it simply involve the distance that your center of mass is moving and your weight? I read some other article that said your legs act as levers, ...
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3answers
2k views

Why do people with bigger hands/wrists have bigger torque advantages in arm wrestling?

I have arm wrestled people with less strength than me who win simply because they have thicker wrists, or larger hands. It has nary to do with having better technique either, because their wrist size ...
4
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1answer
275 views

Anisotropic refractive index with isotropic components?

In relation to my question here I wanted to make sure that my physical argument was not flawed. Anisotropic properties, (especially refractive index) is characteristic of a well-ordered solid ...
2
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2answers
109 views

Quantum uncertainty in cell functions

In class today (philosophy of the mind) we discussed the ideas of Richard Lewontin. He stated that in determining the phenotype of a gene we must take into account the environment but also quantum ...
7
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1answer
595 views

``What is life?'' by a physicist definition [closed]

The question is about defining ``What is life?'' in the field of Physics. Whether there is any (insightful) way of defining ``What is life?'' from physicists. There are pioneer works, including ...
2
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1answer
174 views

Meaning of Lagrange Multiplier in Ou-Yang and Helfrich's Shape equation for Membrane

Dear people in Physics Stackexchange, My question is mostly related to the following papers: U. Seifert, Z. Phys. B 97, 299 (1995). "The concept of effective tension for fluctuating vesicles". U. ...
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3answers
403 views

How does a pressure suit work?

I recently learnt that a suit called pressure suit is worn by fighter plane pilots to prevent red-outs and black-outs. And it seems to be work by - "..applying pressure to selective portions of ...
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0answers
30 views

Suppose we fill a membrane with ferro fluid, and alter the magnetic field around it in specific ways, what dynamics can come into play?

im trying to develop a flexible robotic arm filled with ferro fluid. Different flexible motions can be performed using this concept.
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0answers
38 views

Effects of magnetic fields on our bodies [duplicate]

I worked 20years in a very high magnetic field at an Aluminum foundry. I'm now in my 50's and I don't know or am I aware of any negative effects from this. Is there anything I should be on the look ...
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0answers
56 views

Modeling Acoustic Lubrication

I thought about posting this question in the Biology StackExchange site but really it is just the application of my question that applies to biology not the core of the question itself. Can anyone ...
2
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0answers
165 views

How much energy (eV) is in a mosquito's wing beat?

We're all familiar with the annoying sound of a mosquito near our ear. I estimate the wing beat frequency to be in the 400 to 800Hz range (to accomodate the Bruce Willis and Danny de Vito of mosquitos ...
1
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1answer
3k views

How does the height of a jump change if the body is scaled down?

This is a physics question that appeared in the movie 'The Internship.' If you are reduced to the size of a coin and put into a blender what would you do? Apparently the answer was that with a ...
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0answers
48 views

Reference request: finding a biophysics paper about super time resolution imaging of a neuron firing

About a year ago I attended a talk at the University of Ottawa. The author described a method for achieving super time resolution images of a neuron firing. From what I can recall, the group found a ...
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3answers
948 views

How do human ears distinguish the frequencies in sound?

If they do a Fourier transform, how can they know the formula to find coefficients?
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2answers
1k views

Is any work done when I walk?

I am trying to figure out the amount of work done when I walk X miles or for X minutes. So I got Work=Force x Distance and Force=Mass x Acceleration and Acceleration=(change in velocity)/time. I am ...
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6answers
12k views

Google interview riddle and scaling arguments

I am puzzled by a riddle to which I have been told the answer and I have loads of difficulties to believe in the result. The riddle goes as follows: "imagine you are shrunk to the size of a coin ...
2
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2answers
175 views

Harmlessness of a pure alpha decay particle

From my high school physics class I remember that there are some particles which exhibit pure alpha decay (i.e. alpha decay to there stable isotope), like Po-210, Po-211 and Bi-209. What I also know ...
-1
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1answer
323 views

Temperature gradient in body [closed]

Is there a Temperature gradient in the human body? especially I have heard that the eye is colder than other places? Is that right?
56
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3answers
70k views

Why can Hiroshima be inhabited when Chernobyl cannot?

There was an atomic bomb dropped in Hiroshima, but today there are residents in Hiroshima. However, in Chernobyl, where there was a nuclear reactor meltdown, there are no residents living today (or ...
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4answers
1k views

What is our estimated running speed on Moon's surface?

I was wondering if we have the chance to run on the Moon's surface, how would you expect it look like? I expect our velocity will increase for the same work we do on Earth, but not sure if this will ...
4
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1answer
313 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 ...
16
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2answers
1k 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 ...
0
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1answer
116 views

Atoms in our body

Our body of course exchanges some atoms with environment every day however are there some of atoms which stay with us a life time?
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2answers
30k 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 ...