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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Is it possible to do the stair climber without using any energy?
In gyms I sometimes work out on a stair climber machine. This machine has stairs that move down and you have to climb upward to stay on the machine. I've taken a high school physics class, and I was ...
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Light from an eclipse [closed]
Why do people fry their eyes staring at the sun during a solar eclipse? Is it that they stare at the sun for a long time---longer than if they stared without an eclipse? Or is it that during the ...
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Why does bringing a helium filled latex balloon close to my ear make it feel pressurized?
Title pretty much says it all.
Got my son some balloons for his 1st birthday. He was playing with them while I was holding him and everytime he brought one closed to my ear it made my ear feel ...
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What determines whether colors you can't see are visible or not?
So, when someone is red-green colorblind, the colors appear the same to them, like this:
Source: https://iristech.co/what-do-colorblind-people-see/
And if you're totally colorblind, then things ...
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Calculating jumping distance?
I'm trying to figure out how to calculate the jumping distance of a person or animal based on body weight and initial speed, but I can't seem to find any relevant information online about this. Is ...
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Why does a CT scan with contrast make you feel warm?
I recently had a CT scan with IV contrast liquid. I was warned it might make me feel warm and that this is normal.
I had an amazing sensation of heat moving down my body.
All my searches tell me that ...
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How strong of an MRI machine would be able to kill a person?
Previous title: How strong of a magnetic field could dissociate water molecules?
(Changed as this is probably not possible)
This is part of an attempt to answer the question 'How much MRI is enough to ...
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Why does the length of a person change when they are lying down or standing up?
It's just an observation. I don't know if there is actually a physics theory behind it. I am looking for an intuitive answer.
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Cosmic web distribution and neuron system similarities
Does the cosmic web follow Gaussian distribution? If so, is that the reason it resembles the human neuron system? Does the human neuron system follow Gaussian distribution too?
(sorry if this deviates ...
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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. ...
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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 ...
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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 ...
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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 ...
rob♦
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Stability of plants and buildings: the role of the xylem
Dicotyledon plants show a stem structure with many xylem tubes, hollow but with lignified (woody) walls. These are arranged as in the figure below, in a circle. Their roots, on the other hand, have ...
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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 ...
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Physics of Sound and the middle ear?
Once sound waves reach the eardrum, the eardrum moves back and forth and transmits those waves/pulses to three bones that serve to transmit and amplify the pulses to another "drum" in the ...
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How is the wattage of a human larynx calculated?
This site says the typical human voice has a wattage of about 1W. Another site indicates it is 80db with about 0.001W of energy.
I'm confused.
How does one compare 80db of 0.001W against 1W?
Most ...
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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 ...
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Is there an equation that can estimate chances of alien life in the universe?
Seeing how infinite the universe appears and out of all of those stars, planets, galaxies, there must be other life forms. Mathematically, the odds are very good. Is there a mathematical equation to ...
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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, ...
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How much sky do we see at any one moment?
When we look at any particular point the sky, what percentage of the celestial sphere do we see?
This question arises from the notion that on average there passes one meteor per hour overhead. So ...
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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?
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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 ...
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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 ...
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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. ...
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Physical explanation of seeing sparkles?
I know this might look more appropriate to ask this kind of question on the biology or medical stackexchange but since this kind of cross-science question I'll ask it here.
Sometimes when sitting and ...
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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 ...
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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 ...
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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 ...
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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 ...
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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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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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Relation of time dilation with Biological clock
I have completely understood the time dilation topic along with its mathematical derivation and consequences.
And we know due to time dilation a person's biological clock slows down.So I am not ...
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What force enables us to walk?
When we walk, we apply a force $F$ on the earth at an angle $\theta$ .
Thus, by Newton's third law,
$$ F_{\text{me, earth}}=-F_{\text{earth,me}}$$
Therefore, the earth exerts a reaction force on us, ...
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5G networks and health concerns
Are there any peer reviewed journals on 5G networks and health concerns?
I know very well that 5G radiation is of low frequency and non-ionizing and some concerns are related to the power of the ...
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Is there a depth at which a human body, with lungs full of air, will no longer float?
I was watching a special on divers who dove down hundreds of feet without tanks or gear. The show referred to a depth at which the diver was no longer buoyant and would actually sink, even with lungs ...
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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.
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What is the relationship between the second law of thermodynamics and evolution?
On one hand evolution seems to drive against the second law in that it creates a state of (locally) higher order.
On the other hand the second law seems to drives evolution - in the sense that it ...
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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 ...
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Is it better to do normal or incline push ups? [closed]
⁸You have two possible configurations to make push-ups. In both configurations our arms are placed at 90 degrees from our body. The first position is normal push-ups where. your hands are placed on ...
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How can ultrasound hurt human ears if it is above audible range?
Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz. Then ultrasound is above 20 kHz
Occupational exposure to ultrasound in excess of 120 dB may lead to
hearing loss.
Source
How ...
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What amount of force could be created by a person "swimming" in air?
Had a question on a physics test, a person is at rest on a frictionless surface and can not throw anything, can they move?
I said yes, by "swimming" against the air and got docked because "it wouldn'...
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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....
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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) ...
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Why is unit of pressure (psi) used to determine things like bite force of an animal?
Whether in tv documentaries or journals, whenever they talk about an animal's bite force, it's measured in PSI anytime imperial units are used (ex: National Geographic, NIH Journal). Many even seem to ...
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