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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1answer
43 views

What forces the maximum speed of a cyclist on a steep climb?

I know that on a flat road drag is the main force, I have to provide as much force as the drag (and the friction in the drive train) produces. I can also see that the faster I ride, the harder it gets ...
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1answer
33 views

Experiments in ISS

Recently a Japanese capsule brought back proteins that were created in ISS in the absence of gravity. Researchers will study them to "understand their folding better". My question is, regarding ...
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1answer
160 views

What are the main causes for eyeball becoming too long or short in myopia and hyperopia? [closed]

myopia and hypeopia occur due to change in eye ball size or lack in cilliary muscle ability to accomodate. \n\n But why in lasik laser operation , the one's cornea shape is changed rather than acting ...
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2answers
121 views

Symptoms of lethal neutrino radiation in a hypothetical scenario

Core collapse supernovae release the majority of their energy in the form of neutrinos. According to an XKCD What If, the neutrino radiation alone from a supernova at a distance of just 2 AU would be ...
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8answers
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Is it possible to squat quicker than gravity?

It's definitely possible to propel your body using muscle to move towards the ground quicker than gravity. But is it possible to squat quicker than gravity? Assuming squatting from your knees and ...
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2answers
66 views

Does duration affect how lethal a current is?

It's been said in many places that it's not voltage that kills you but the source's current (or more so a combination of the two), but take a current of 0.1A which can be considered fatal. Would a 0....
2
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1answer
46 views

Do we have enough time for understanding space? [closed]

May be there more big bangs out there... while studding about space i some times think about a bacteria living on my body that may have a life span of 5 seconds if it has logical understating even ...
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2answers
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Energy that can control itself (A unit that can process information without body) [closed]

I read a book called The future of the mind. There it suggested a conscience that exists in the form of energy without body. Ideally, I thought the energy without body may take the form of light. ...
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3answers
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Humans have an average energy budget of $100$ Watts, but the power radiated from the body is $1000$ Watts?

On average a human consumes around $2000$ kilocalories per day. This converts to roughly $2000000$ calories / $86400$ seconds or around $100$ joules / second giving roughly $100$ watts. But if you ...
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2answers
60 views

Perception of curvature of human eye [closed]

How are human eyes able to detect the different curvatures of surface ? Basically how are the human eyes able to differentiate between a plane surface and a convex or a concave surface?
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2answers
208 views

Bernoulli's Effect on Blood Pressure [closed]

What is the impact of height, let's say being on top of a 4,000 m high mountain, on blood pressure / flow velocity given Bernoulli's Equation?
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1answer
566 views

What is the “comfortable” acceleration in a curve and braking in a car? [closed]

A car that makes a curve or a braking will naturally have its horizontal G-Force altered according to its speed and the intensity of the braking or the angle of the curve. My question is: which ...
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1answer
55 views

Would humans die of old age on an interstellar/intergalactic voyage? [duplicate]

It is often claimed that if we ever sent humans to colonize other stars, we would have to send them on generational ships. However, if the ship traveled at $99.9\cdots 9c$, wouldn't the passangers' ...
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2answers
108 views

Question about lenses in the human eye

To see near objects,the ciliary muscles contract and the suspensary ligaments loosen,making the lense thicker. İ don't understand how that helps us to see distant objects . To see distant objects ...
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2answers
51 views

Force, work and the apparent disappearance of Mechanical Energy [duplicate]

A man exerts force on a wall of bricks. The man must have consumed the energy he possessed (mechanical energy?) to exert the force. The man sweats and tires himself out but the wall does not move. ...
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6answers
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How does light combine to make new colours?

In computer science, we reference colours using the RGB system and TVs have pixels which consist of groups of red, green and blue lines which turn on and off to create colours. But how does this work?...
3
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2answers
432 views

Why might Roger Penrose argue that Godel's incompleteness theorem(s) suggest that consciousness is non-algorithmic? [closed]

This past March, when I called Penrose in Oxford, he explained that his interest in consciousness goes back to his discovery of Gödel’s incompleteness theorem while he was a graduate student at ...
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1answer
66 views

probability density distribution: From free diffusion to presence of a barrier

I am a biologist and I am not very comfortable with statistical mechanics. However, I want to learn and I am trying to understand. I just need some clues from people that handle these topics easily. ...
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2answers
31 views

What is the optimal light setting for human vision? In other words, is my vision better during the day or at night?

There seems to me to be two main effects that should be considered in answering this question. The first is that the iris dilates in low-light settings, which causes an increase in the numerical ...
2
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1answer
2k views

How many calories in a block of wood?

I was recently thinking about the human body and the energy we get from food. I understand we don't have the ability to properly digest certain things like stones and wood and grass, but if we did, I ...
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1answer
84 views

Why universe is so perfectly made for us? [duplicate]

I am very eager to learn that, "Why universe is so perfectly made for us?" Or our universe is just stable by chance?
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1answer
46 views

Same amount of calories burned for half the reps and double the weight? [duplicate]

So I was looking at the work= force x distance equation and was just wondering if for example I normally do 100 dead lifts at 100 pounds. Would I get the same calories burned if I did 50 dead lifts ...
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0answers
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Has anyone ever actually considered a spherical cow? [closed]

Yes, I'm aware this question is somewhat whimsical. I'm sure every physicist is familiar with "Consider a Spherical cow". Has a cow (or any animal for that matter) ever been assumed spherical for ...
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2answers
52 views

What if the luminosity of Sunlight increased by 10% [closed]

If the luminosity of sunlight increased by 10%, would people be able to survive outside? Would such brightness of light be very harmful to them, for exemple as much as the Mercury Vapour Lamp without ...
41
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3answers
7k views

Can ants walk on liquid mercury? [closed]

I'm not a physicist, but I was wondering: Can ants walk on dense liquid like mercury and why?
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1answer
154 views

Freeman Dyson: Advanced intelligences thinking in an expanding universe [closed]

I dont know if this is the correct place to ask this, because is highly speculative and maybe even hard scifi. But... I think is less speculative than the many worlds interpretation of QM or many ...
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2answers
349 views

Is the universe really “fine-tuned for life”?

I understand what is meant when we say the universe is "fine tuned", but I've seen it claimed it's is fine tuned "for life". Is it? When I look at known or even speculated life in our universe, I see ...
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3answers
85 views

What is the relationship between the amount of radioactive substance and the harm it does to the body?

This is probably a very simple question, but I wonder how the amount of radioactive substance is related to the radiation it emits and therefore the harm it does to the body. If I held 0.1g of barium-...
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0answers
120 views

How do hypermetropic people see objects beyond the focus of their convex corrective lenses?

The way I have developed intuition about optics suggests that humans can only see objects if two rays of light that originally emanated from the same point reach the eye in a way such that when ...
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0answers
108 views

Why are there limits on physics' applicability? [closed]

(Not sure if this is the right SE for this question). Physics is great at predicting what inanimate stuff do. Why can't it also predict what living things do? For example, if I throw a ball off a ...
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54 views

Why animal eyes see the spectrum from red to violet?

Maybe this would not be proper question on physics stack exchange, but it originated from physics book so I'll post it here anyway. I have much interest in color recognition evolution. I'm studying ...
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2answers
76 views

If you are ontop of a giant heavy object that is falling from the sky, is it possible to jump and roll at the perfect time to survive? [duplicate]

I don't know if gravity or the speed of the drop would prevent us from jumping, but would something like this be possible? If it's not possible on the ground, is it possible in the ocean? I'm sorry ...
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2answers
600 views

Implications of parity violation for molecular biology

In biology, the concept of parity emerges in the context of chiral molecules, where two molecules exist with the same structure but opposite parity. Interestingly, one enantiomer often strongly ...
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1answer
84 views

Internet - mobile phone vs wifi

wifi cost me like 30USD while mobile internet 10USD, I thought to save this monthly bill by purchasing a mobile-phone-router. The only thing that blocks me from that is radiation. I'm far fetched ...
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1answer
99 views

Why has it taken so long for people to talk about using Far-UVC light for disinfecting?

If you don't know what I am referring to you can see this simple TED talk https://www.youtube.com/watch?v=YATYsgi3e5A. There are also many articles online about it. After watching that TED talk, all ...
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3answers
229 views

Why can I see the glow from my TV remote's LED if it is supposed to emit in the infrared?

The TV remote light emissions being >700nm are supposed to be invisible right? Same goes for proximity sensor on phone and laser focus on phone's back camera. But how could, me and 3 more people I ...
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2answers
411 views

Thermal Radiation of human body

I've read that all bodies emit electromagnetic radiation of all wavelengths. Does this mean that humans emit gamma rays too (excluding the radiation from radionuclides present in humans)?
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2answers
43 views

What is the enviroment in which water will come out of an ice fishing hole?

I have watched some videos on YouTube of people cutting holes in ice and water not just finding equilibrium in the hole, but water actually coming out of the hole along with many fish. There has to be ...
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1answer
142 views

How dangerous is a neutrino experiment near human habitation? [duplicate]

I just read about people trying to capture neutrinos and study them. America has a lab in Antarctica and France deep under the ocean. Is it dangerous to conduct such an experiment where people live or ...
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1answer
394 views

Does Square Cube Law always hold? [closed]

There is a video that has been doing the round for a few years of an MIT lecture that has become a topic of debate in another forum I am a member of. The lecture by Prof Walter HG Lewin discusses ...
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1answer
80 views

How much energy burned during human walking exercise? [closed]

Let's assume that a person walks on a flat surface. Work performed by a human can be calculated by this equation: $W=F*s(1)$, where $F$ is a force and $s$ is a distance. I am curious how mobile ...
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1answer
101 views

Understanding the color of fluorescent and non-fluorescent objects

I am trying to read up and understand a lot about how normal looking objects like chairs are visible to us as compared to fluorescent substances. This question says that - "It is often said that ...
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2answers
142 views

Neutrino project in Tamil-Nadu India [closed]

In Tamil-Nadu, the Indian government is going to start a neutrino project. Questions: Is it harmful for people who stay there? Will this project affect any living beings? Does it cause any ...
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2answers
94 views

Why does yawning distort headphone music?

During deep and prolonged yawning, I noticed the music tonality is distorted: the pitch becomes slightly lower. Why?
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1answer
89 views

Are there examples of history dependent quantum dynamics that evolve like biological life?

There are examples of time evolution of quantum dynamics with history dependence, such as these quantum random walk examples which make use of a memory parameter to influence the distribution of the ...
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0answers
317 views

Is it possible to prove that an elephant and a human could jump to the same height? [duplicate]

Is there a physics argument, based on scaling, that leads to the conclusion that an elephant and a human could jump about same height? Could this be extended to any two creatures with different ...
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0answers
29 views

When we push a wall, we get tired Why? [duplicate]

When we push a wall the wall does not move so, no work is done but still we get tired Why? What energy changes occur in this process.
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1answer
136 views

How long could someone survive in free fall? [closed]

If there was hypothetically a bottomless pit (no ground), then approximately how far down could you possibly survive without being killed by the speed? (there is no vacuum so air resistance matters.)
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2answers
79 views

Is 220 V, 50 A equally dangerous for a person as 1A, 11000 V? [duplicate]

The question is self-explanatory. I'm a high school student so feel free to use scientific terms.
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2answers
63 views

What do we call these energy forms?

First of all I apologize for the basic question. When we throw a ball upwards, energy gets converted from us to kinetic energy which becomes potential energy and as the ball falls back down it ...