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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Safe Distance from UV tanning bulb [closed]

Good morning, I am just wondering how far the uv rays can travel from a tanning bed especially when it is open. I assume if you were in the same room it would be dangerous but do they travel further ...
Graham Stone's user avatar
1 vote
1 answer
41 views

Why and how white noise cancels other background noises?

This idea of white noise cancelling other background noises is quite popular these days and I always wonder how it works? https://www.youtube.com/watch?v=nMfPqeZjc2c This is a sample of white noise. ...
Devansh Mittal's user avatar
0 votes
2 answers
74 views

Is holding a falling object the same effort as lifting it?

It seems like lifting objects requires more effort compared to dropping them, although the law of conservation of energy still applies. As discussed Physics Stack Exchange answer, energy transfers ...
Manticore's user avatar
  • 103
1 vote
2 answers
115 views

Is it plausible that Earth's magnetism can induce heart attacks by affecting red blood cells? [closed]

https://ui.adsabs.harvard.edu/abs/2014cosp...40E1114G/abstract#%3A~%3Atext%3DIt%20was%20shown%20statistically%20that%2Ccomparison%20with%20quiet%20geomagnetic%20conditions This study says that on ...
Malcom's user avatar
  • 39
0 votes
2 answers
52 views

Why do the proteins in our eye have a continuous (bell shaped) absorption spectrum?

From quantum physics, I would expect that seeing e.g. red would excite the 564nm energy level of the Photopsin protein. I would also expect to only see (apart from some small smeering out) that we are ...
mtooling's user avatar
0 votes
1 answer
39 views

How wave speed affects perception?

If there were 2 sound waves with the same wavelength and amplitude, but different speeds, how would my perception of the waves vary? How would my perception vary if they were light waves instead of ...
VV_721's user avatar
  • 33
1 vote
2 answers
54 views

Would quantum superposition stop if we observe the particle in the case of photosynthesis?

I started looking up more into quantum biology from photosynthesis to genetics mutation and how they are explained by quantum properties. my question is about the case of photosynthesis: quantum ...
Rihab's user avatar
  • 11
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0 answers
18 views

Na+ and K+ ions and EMF [duplicate]

I understand that electrons moving in a conductor will generate photons by colliding with the conductor lattice and that this generates photons. What about Na+ or K+ ions in a salt solution, ...
kevinohlemiller's user avatar
0 votes
1 answer
63 views

Why does cigarette smoke stay so stubbornly on our bodies? [closed]

How does anything stick to anything, for that matter? Another example: why does perfume also stay so stubbornly on our bodies? And why do some perfumes stay longer than others on a fundamental level?
damacc's user avatar
  • 9
-1 votes
2 answers
54 views

How do dark color varies from people when seeing the back of their eyelids?

Depending on the light source, the back of people's eyelids either be black or dark gray depending on what lit environment they're in? the how does eyes function when people have the back of their ...
Amber Alvia's user avatar
19 votes
6 answers
3k views

Can human ear hear 4 Hz frequency, if I tap my hand 4 times per second on table?

Frequency means the number of repetitions per second. Humans can hear between 20 Hz and 20 kHz, but I have a very basic question: if I tap my hand four times on a table per second, it means I am ...
Avinash Agrawal's user avatar
8 votes
5 answers
2k views

Do colours which are not visible to human eyes exist?

Are there any colours that our human eye cannot comprehend but other animals can see? The ability to see colours is the property of our eyes. For example an average dog would see less colours than us. ...
Aleph's user avatar
  • 412
2 votes
5 answers
221 views

Power Generation in a Bicycle

Consider a person pedaling a bicycle, if we consider the system consisting of the rider and cycle as a total and apply work energy conservation we can see that whatever force the rider applies on the ...
L lawliet's user avatar
  • 297
-4 votes
1 answer
80 views

Are there laws of creation for biological life? [closed]

I am no scientist, but I do love science as well as the unknown. Are there laws of creation for biological life? Would it be safe to assume that our bodies are made up from things that came directly ...
The Grout Savior's user avatar
1 vote
2 answers
47 views

Optimizing accuracy of different basketball shots [closed]

I have a high school math project and chose to work on basketball trajectory because I thought I would enjoy it the most. But honestly, I have a hard time calculating a 3D trajectory. So I thought ...
Nicolas's user avatar
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1 answer
121 views

Could a human-sized flea really jump over the Eiffel Tower?

I am puzzled why so many people think such a large flea could jump as high as the Eiffel Tower. We know that a 3mm long flea can jump 150mm, which is 50 times its own length. So I suppose it's ...
Brian F's user avatar
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18 votes
3 answers
22k views

Why did these algae grow like this in the pool? Are these curves the gravitational equivalents of the bell curve?

My friend sent me these pictures of a pool that has been abandoned for a long time, and we are curious about the reason behind the peculiar growth of algae in this pattern. The needle-like towers of ...
Tripasect's user avatar
  • 318
12 votes
5 answers
2k views

Why is cycling easier while standing on the pedals?

On high slopes and rugged terrains, riding a bicycle while standing on the pedals is easier. Even though I cannot physically define what is "easy"; since it is a feeling that my body ...
AlphaLife's user avatar
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0 answers
274 views

How fast can the human hand move?

I was playing with my six year old daughter the other day with her toy airplanes (I’m a pilot and she’s very interested in aviation now). I took the little F16 toy and flew it passed her as quickly as ...
Cjh199712's user avatar
1 vote
0 answers
97 views

Is there a depth under which the buoyant force is no longer sufficient to bring a diver back to the surface? [duplicate]

I came across the story of diver Yuri Lipski who died while diving in the Blue Hole. This made me wonder something and it may be a stupid question but I thought I'd ask: For a human diver with normal ...
Fermin C's user avatar
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0 answers
32 views

How do Radical Pairs Result in Magnetoreception?

An Immense World by Ed Yong is a fantastic book on sensory biology and has a great section on magnetoreception. Although it is confirmed with behavioral studies that many species of birds have ...
E Tam's user avatar
  • 95
10 votes
2 answers
3k views

Reverse blood flow in an IV

When the IV drip for a patient is completed, the patient's blood will flow back. This is apparently due to the pressure difference. However, IV needles are inserted into veins in the direction of ...
Starlight's user avatar
  • 285
-1 votes
2 answers
68 views

Is this statement accurate: We are 4D beings (l,w,d,t) with the ability to visualize in 3D (using our brain) and see in 2D (using our retinas)? [closed]

I've read conflicting information on us being 4D beings (length, width, depth, time) and in what dimension we are able to see. Interested to hear your thoughts, especially if you provide sources.
Benjamin Awerkamp's user avatar
10 votes
2 answers
4k views

Is it correct to say that "WE" feel only 5/140 of the actual weight of brain as buoyancy acts on brain due to cerebrospinal fluid?

Many sources of biological sciences (e.g.https://medium.com/@drvnx/what-is-that-thing-without-which-we-are-dead-f556fb1029ef ) say that the actual weight of brain is almost 1400gwt but as brain ...
Shinnaaan's user avatar
  • 1,219
0 votes
1 answer
140 views

Can the human eye see the images of 300 nm light on a screen through a diffraction grating?

In my textbook there is a question as follows: A diffraction grating with 200 lines per mm is placed between a monochromatic light source and a screen. The distance from the grating to the screen is 2....
Kantura's user avatar
  • 1,315
30 votes
7 answers
8k views

Why does blowing a whistle in someone's ear damage it more than blowing directly in their ear? Won't the whistle reduce overall energy?

If I blow really hard from a whistle near someone's ear, it'll hurt a lot. But if I blow directly at a person's ear, it won't hurt nearly as much. But shouldn't the whistle (or any other obstruction) ...
chausies's user avatar
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1 vote
0 answers
56 views

How long will oxygen last in a $3\times 3\times 3 $ meter room for one person? [closed]

Let's assume that the windows and doors are tightly closed. How can I calculate at what moment I will feel a lack of oxygen and my well-being will worsen? Can one person completely consume all the ...
Tamila Ambeon's user avatar
13 votes
7 answers
5k views

Are human eyes interferometers?

It seems like 2 eyes is enough “wetware” to do interferometry inside brain. Can you definitely see some reason why this could not be happening, or some way to test if it does happen?
Euphorbium's user avatar
0 votes
1 answer
152 views

Does the human brain use random number generators? [duplicate]

Neurons fire depending on the impulses they get from other neurons. This seems to be 'deterministic'. However, sometimes it might be useful to use random processes instead. Does the human brain have ...
Riemann's user avatar
  • 1,407
5 votes
1 answer
224 views

Generation of order on the Earth

I learnt in a course on Biological Physics that it is possible to generate order without violating the second law of thermodynamics. This can be done if "high quality" energy is delivered to ...
eeqesri's user avatar
  • 1,477
1 vote
2 answers
69 views

The sun's neutrinos and the brain [closed]

Is it possible for the sun's neutrinos to be detectable biologicaly . Or what is the simplest way for a experimenter to detect neutrinos externally?
Levimega's user avatar
1 vote
1 answer
100 views

Question about the 2nd law of thermo

In some ways the 2nd law of thermodynamics appears to be violated by the creation of large molecules like proteins. The reason this seems to be a violation is because individual atoms become much more ...
scl's user avatar
  • 95
-4 votes
5 answers
412 views

How is abiogenesis not a violation of the second law of thermodynamics?

Randomly traveling molecules plus random changes in temperature, pressure, acidity, electric charges equals a cell. That is a decrease in entropy. How does that not violate second law of ...
Bob's user avatar
  • 137
0 votes
1 answer
404 views

What happens, if amino acids are exposed to extreme heat?

What will happen to amino acids if they are exposed to extremely high temperature such as the temperature of the Sun? Do the amino acids become more simple structures?
SnoopyKid's user avatar
  • 342
12 votes
2 answers
2k views

Which electrons kill you during electrocution?

I understand that there are three velocities in play in a circuit (I haven't studied Physics past high school so give me some rope) v1: the velocity by which the electrical field propagates through ...
Marcus Junius Brutus's user avatar
0 votes
3 answers
513 views

Out running a bear

I was going to ask this in wilderness but I’m pretty sure we’ll need some math to find out the real answer. They say you can’t out run a grizzly bear because they run about 35 mph. While the average ...
Luke's user avatar
  • 125
5 votes
3 answers
499 views

What's the reason that it requires less effort to walk against an escalator (to stay stationary) than walking up stairs?

I had this discussion with my relatives about the reason why it feels like you spend less energy on a step machine in the gym (basically an escalator that goes down), than it is to move up some stairs....
user3635700's user avatar
2 votes
0 answers
84 views

In theory, how fast could I possibly serve in a game of ping-pong?

A tennis player can serve in a more or less straight line from their racket to the service box on the other side of the net: there's a direct line of sight. That means that there's no inherent limit ...
Daniele Procida's user avatar
2 votes
3 answers
135 views

Are bacterial flagella the most efficient propulsion system at the microscopic scale?

Bacterial flagella can be regarded as microscopic propellers. The rotor is a long, helical protein filament powered by proton gradient. When protons pass through the gap between the rotor and stator, ...
哲煜黄's user avatar
  • 1,435
0 votes
2 answers
116 views

The *compressive* strength of spider silk

There's plenty of information about the tensile strength, density, energy density, ductility, etc. of spider silk. However, I personally cannot find any figures in regards to the compressive strength ...
KEY_ABRADE's user avatar
-2 votes
2 answers
102 views

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 ...
Jonatas's user avatar
0 votes
1 answer
131 views

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 ...
Muhammad Ikhwan Perwira's user avatar
1 vote
1 answer
90 views

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 ...
p1l0t's user avatar
  • 113
-2 votes
1 answer
59 views

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 ...
debtitor's user avatar
-1 votes
1 answer
41 views

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 ...
Vanshika Sejwani's user avatar
0 votes
2 answers
64 views

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 ...
joeyfb's user avatar
  • 121
0 votes
2 answers
258 views

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 ...
Chahak's user avatar
  • 468
0 votes
2 answers
207 views

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 ...
StackQuest's user avatar
14 votes
6 answers
5k views

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 ...
Markoul11's user avatar
  • 3,841
1 vote
0 answers
73 views

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 / ...
User5754448's user avatar

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