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-3
votes
1answer
69 views

Are atoms bad and good? [on hold]

Is there a concept that means classifying over good and bad atoms? Why the atoms in a particle of dust or contamination are unhealthy and the particles of something organic is healthy? Why some stuff ...
0
votes
0answers
26 views

Suggestions for Thesis on possible areas of Biophysics [on hold]

I am currently doing my Masters in Physics, and I am planning to start my Thesis this summer on any one areas of Biophysics which I found quite broad to look for and I am struggling to choose any one ...
16
votes
1answer
1k views

How long would it take for a smelly object to evaporate?

This question is a follow on from this deleted one: http://physics.stackexchange.com/q/177894/26076 as I was writing what I thought to be a valid physics answer to it. Version 1 of this question ...
-2
votes
0answers
32 views

How do I convert a specific absorption rate from W/kg to eV/kg/ps [on hold]

Specific Absorption Rate (SAR) is the rate at which electromagnetic energy is absorbed by water, human tissue or any other material. After performing an electromagnetic simulation i got the below ...
0
votes
2answers
25 views

How can plants rooted on the ground become charged?

According to a quote on the physics forum "Plants are usually charged negatively and emit weak electric fields." Reference However this seems to contradict the fact that plants are grounded and any ...
0
votes
1answer
55 views

Why does the sky look blue rather than violet? [duplicate]

Sky looks blue because because our eyes are sensitive to blue colour. But when viewed through a camera why don't we see violet of the sky even though we can see violet colour of other pictures taken ...
1
vote
1answer
193 views

Remote EEG detection / reading

I recently noted that Phillips, Accenture, and Emotive grouped together to create a proof of concept that would assist ALS patients to gain greater control of their lives through brain, voice, and eye ...
1
vote
2answers
52 views

Singing for physicists: How to resonate by body cavities with my voice?

My body has various cavities, such as my throat, mouth, chest, and nose. This cavities have resonant frequencies. I also have a voice box, which creates sound. How do I create sounds at the resonant ...
0
votes
1answer
25 views

Factors affecting pain of static electricity shock

Referring to How to avoid getting shocked by static electricity?, someone I knew suffered much pain from static electric shocks when touching door knobs or car doors where I didn't feel anything doing ...
-1
votes
0answers
37 views

In an all-out nuclear war, how long should remain sheltered? [migrated]

Fairly common in sci-fi literature is the scenario where the Earth is destroyed by an all out nuclear war. Typically, the protagonist have survived by remaining in underground shelters for decades ...
16
votes
6answers
10k 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 ...
5
votes
2answers
1k views
10
votes
2answers
1k views

Why is pale coloured skin said to absorb more UV?

Many resources state that light skin/pale skin absorbs more UV than dark-colour skin. Doesn't black absorb maximum radiation? For an example, see this article: Natural selection therefore ...
0
votes
1answer
113 views

Is the strength of a muscle proportional to its cross-sectional area?

I have a question that is partially related to at least a couple of old questions: this one and this other. My question is specifically focused on the following point: why should the strength of a ...
1
vote
0answers
100 views

Visualise the sound intensity

I'm studying Biophysics and my current subject is sound. One of the properties of sound is intensity. From my notes I can see the following definition: Intensity Formula is: $(I = w*m^{-2})$ or $(I = ...
1
vote
1answer
61 views

Physics involved in the DNA-structure discovery

In 1962 Francis Crick, James Dewey Watson and Maurice Hugh Frederick Wilkins won the Nobel Prize: For their discoveries concerning the molecular structure of nucleic acids and its significance for ...
0
votes
2answers
53 views

Laser tattoo removal

I would like to know if someone could please briefly explain how laser technology of tattoo removal works? And second, could there possibly be any dangers to cells, specially on bones?
5
votes
6answers
1k views

Why do we lift our feet when we walk?

I'm not sure if this is a good question for here- albeit if I asked it somewhere else I'd want the physical argument. Why do we lift our feet when we walk, as opposed to doing something like ...
-1
votes
1answer
46 views

Top speed for a human

What is the fastest that a human being of average weight could possibly travel, and what is the most widely held theory for how this might be achieved (assuming this person is impervious to all forms ...
8
votes
3answers
8k views

Does the human body have a resonant frequency? If so, how strong is it?

Inspired by this question on Music beta SE, I'm wondering if the human body has a strong resonant frequency. I guess the fact that it's largely a bag of jelly would add a lot of damping to the system, ...
0
votes
0answers
20 views

Frequency resonance of Bones, and other parts of the human body [duplicate]

Today in class we were learning about states of matter. I found out that in a solid the atoms are vibrating. This caused me to think about how crystal glass will break if an opera singer sings high ...
1
vote
2answers
262 views

Human Muscle Energy - Increases or Decreases by doing work?

When Human does some work, he gets tired. I will think he looses some energy. If he really loses energy by doing work how does he gain more strength to do more work later. His muscles become strong ...
7
votes
4answers
3k views

Can the brain detect the passage of a neutrino?

On a few occasions either in bed or sitting around a fire, with my eyes closed, I rarely but sometimes see a very quick fast flash of white and then, with my eyes still closed, the flash disappears ...
56
votes
3answers
6k views

How can ants carry items much heavier than themselves?

This morning I saw an ant and suddenly a question came to my mind: how do ants actually carry items much heavier than themselves? What's the difference (in physics) between us and them?
3
votes
2answers
807 views

Why does adding red light with blue light give purple light?

Our eyes contain 3 photoreceptor cells (cones) to perceive three wavelength ranges of light. Here is a visual representation of the wavelengths by these receptors (S, M and L). So if we have light ...
5
votes
4answers
112 views

How would swimming in low gravity work?

Sorry I know very little of actual physics, I'm not looking for hard and fast numbers just a general idea of how the mechanics would work. For the sake of argument, say you were on a planet or moon ...
15
votes
4answers
3k 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. Transcription: ...
0
votes
4answers
61 views

Using formula for work with distance of 0m [duplicate]

Consider this: Wind is pushing a huge rock towards me at with massive force at 2m/s. I push against the rock at equal force so the rock stays still. I am clearly "working" very hard, using a lot of ...
0
votes
0answers
28 views

Will increased air pressure increase efficiency of solute diffusion into a membrane?

Biophysics question: I have a container with a biological tissue inside of solution where the solute slowly diffuses across the membrane and binds inside of the tissue. If I were to put this unsealed ...
2
votes
2answers
347 views

What are the main issues that are preventing a human mission to Mars? [closed]

Is it just because it'd be very expensive? Or are there serious problems that need to be dealt with, studied and solved? If so, what are they?
0
votes
1answer
23 views

a question regarding Fourier transform in electron microscopy

I have recorded a micrograph of a 2-D array at a magnification of 43,000x on my DE-20 digital camera, which has a 6.4 μm pixel size and a frame size of 5120 × 3840 pixels. This magnification is ...
1
vote
1answer
53 views

Molecular simulation applied to astrobiology

There is some research group which use molecular dynamics simulations to study the origin of life according to the hypothesis of abiogenesis? I'm just beginning to know this subject so I don't know ...
1
vote
3answers
973 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 ...
-1
votes
1answer
49 views

What is one human power? [closed]

some time ago I was asked what the HP equivalent of a human was, looking into this apart from in the creation of steam engines the power definition 1 Horse power was set at the work of two of the best ...
0
votes
0answers
18 views

A simple derivation of the generalization bounds for the classical perceptron model

I'm basically referring to the great work of Elizabeth Gardner in this matter. I find that her work is often overlooked in the field of neuroscience, arguably because it is too difficult to understand ...
0
votes
3answers
64 views

Work power and energy

When you push your bicycle up on an inclined the potential energy of the bicycle and yourself increases. Where does this energy come from?
1
vote
0answers
56 views

How much energy does it take to hold a bag? [duplicate]

I'm holding a bag with some mass $m$. The force required for not letting it fall is equal to its weight $m \cdot g_L$ (where $g_L$ is the local gravity, assuming Earth this is $\approx 9.8 \; \text{m} ...
6
votes
1answer
209 views

Why do I hear a deep rumble when I cover my ears?

Probably a trivial thing but a simple google search didn't show anything relevant about it. If I cover both of my ears with my hands, I hear a very deep rumble. If I slowly move my hands away the ...
2
votes
0answers
63 views

What biology knowledge can be applied in physics? [closed]

After asking a commensurate question in Biology.SE (What physics knowledge can be applied to biology of organisms and ecosystems?), I wonder about the reverse direction: What biology knowledge can be ...
1
vote
1answer
147 views

Polonium tea emergency [closed]

Let's assume that I just realised that tea I drunk 30 minutes ago during meeting with a secret agent was doped with radioactive polonium. What should I do? What the doctors will do? Are there ...
2
votes
2answers
487 views

Does staring at a bright LED light damage your eyes?

According to this article it seems that it is the UV part of the spectrum from the Sun that causes damage to the eye. Would it therefore be "safe" to observe directly an equivalent energy density LED ...
0
votes
0answers
57 views

Can high osmotic in nerve, intracellular concentration, lead to 'pumping up' nerve cells, strongly increase internal pressure, myelin sheath broken?

On: http://biology.stackexchange.com/questions/6916/can-in-the-case-of-multiple-sclerosis-ms-a-too-high-osmotic-pressure-in-the-n I read a question: Can in the case of multiple sclerosis (MS), ...
0
votes
1answer
61 views

A parameter to quantify instability in flight

Suppose I have plotted the body angles of a flying aeroplane.I have two such plots. One of a normal plane, and the other plot in which a primary sensor of the aeroplane is removed. So with the absence ...
8
votes
3answers
2k 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 ...
9
votes
1answer
555 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 ...
2
votes
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 ...
-2
votes
1answer
97 views

Possible dangers of power lines radiation, wi-fi and gsm technology [closed]

I'd like to know more about the topic mentioned in the title. I have 3 questions. I'd be happy to hear your thoughts on any of those. So if high voltage power lines can cause harm to a human in some ...
3
votes
3answers
3k 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 ...
18
votes
8answers
2k views

What's the difference between running up a hill and running up an inclined treadmill?

Clearly there will be differences like air resistance; I'm not interested in that. It seems like you're working against gravity when you're actually running in a way that you're not if you're on a ...
2
votes
1answer
167 views

Would a six-inch person face certain death when falling from a great height?

In Mary Norton's The Borrowers Aloft, the borrowers are like humans in every way except size - normal adult height is six inches. One family of three is captured by a human couple and housed in an ...