All Questions
Tagged with everyday-life biophysics
52
questions
5
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3
answers
377
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Why do most fish wiggle their tails side to side, and not up-down?
Is moving a vertical fin side to side more efficient than moving a horizontal fin up and down in water for fish locomotion? The answer might lie in how fish propel themselves using vortices, but I don'...
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3
votes
1
answer
95
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Bicycle Uphill vs. Walking Uphill
When bicycling uphill, I have noticed it takes a enormous amount of effort compared to just walking uphill. However, when on level ground, bicycling seems to take considerably less effort than walking....
- 53
0
votes
0
answers
24
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Effects of chromatic aberration in the human eye
Due to metamerism, many different light spectra can be used to show a white colour.
If I understand it correctly, it is even possible to make white light by combining only two monochromatic light ...
1
vote
0
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33
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What was Grant Holloways top speed in his 12.81s 110m hurdle run using kinematics? [closed]
I am a currently a introductory biophysics student and I am attempting to analyze Grant Holloway's 12.81s 110m hurdle run. I thought the best approach would be to break the run into stages due to the ...
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1
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1
answer
1k
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What takes more energy? Walking up stairs or ramp over the same height?
Often when we go hiking, we encounter two kinds of paths whenever we have to cover elevation. We either go up via stairs or via walking up a ramp. Sometimes both are available side to side. And it's ...
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2
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211
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Can humans feel artificial light? [closed]
I know humans can feel sunlight - even blindfolded, it's easy to tell if one is in the noon sun or indoors. However, I don't know about artificial light. Can humans feel sufficiently harsh artificial ...
- 21.4k
3
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1
answer
359
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For weighted pull ups, how does positioning the weight below the hips (eg a dip belt) make the motion harder than when placed on the back (eg a bag)?)
I have been doing pull-ups for a while and decided to recently transition into weighted pull-ups for more growth. When gathering advice, I discovered that placing a weight between the legs, with the ...
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33
votes
11
answers
12k
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Why does running spend more energy than walking?
The study energy expenditure of walking and running concludes that running spends more energy than walking.
My understanding is that although running makes one feel more tired, that only indicates ...
- 534
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2
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2k
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Atom or Cell? Which is the basic unit of life? [closed]
As it is said that everything in this universe is made up of atoms and molecules and atoms are called the building blocks of matter. But then why the cell is called the basic unit of life, why not ...
- 231
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2
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69
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What scientific evidence is there for the definable real world quality of redness independent our perception? [closed]
With light poise and counter-poise, Nature oscillates within prescribed limits. Yet thus all arise the varieties and conditions of the phenomena which are present to us in space and time. - Goethe
...
- 107
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1
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48
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Has physics ever tried to explain how do we get "sensorial experiences"? [closed]
To be clear about what I mean with "sensorial experiences", let's take for example our visual experiences. Certainly, physics (and other sciences) explains a whole process which involves light ...
- 1,252
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11
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1k
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Is it more work to put more (apparent) effort to get the same outcome?
I was taking my dogs for a walk yesterday evening when this question occurred to me.
The two dogs were pretty enthusiastic about the walk and wanted to run on ahead, so the leads were taut and they ...
- 257
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5
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6k
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Why we can't jump without bending our knees?
I observed it while trying to jump from my bed with my knees straightened and I failed to do it. I want to ask whether it is with all of us our it may be a medical issue with me?
Why we can't jump ...
- 3,377
5
votes
2
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6k
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Why does a person carry more weight when sitting down?
Today, while shopping for a chair at a shopping mall, I saw this poster regarding the amount of weight a person is carrying when doing various activities. When standing upright, one carries 100% of ...
- 3,745
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1
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671
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Motion of head during sneezing
When we sneeze, our head moves forward.
However since the air from our mouth moves forward with a high velocity, shouldn't the head should recoil backwards (like a gun, to conserve the momentum) ...
- 706
2
votes
2
answers
178
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Newtonian Physics vs Metabolic Equivilant (MET) calculations
I am trying to help my daughter do her physics homework. Her assignment includes calculating Calories worked off while exercising.
The formula she is using is ...
- 131
3
votes
2
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475
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Human body as a measuring instrument
One can easily find descriptions of human eyes and ears used for measuring phenomenons. Finding what resolution do eyes have or what frequencies can human hear is no trouble. It is also seen in scales ...
- 59
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1
answer
2k
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The physics behind the Judo "hip throw"
Recently, I saw my friend, the Judo captain, easily defeated his much larger opponent with the famous "hip throw" as shown here. Upon researching, I found out that this throw can allow a weaker ...
- 3,745
67
votes
15
answers
22k
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Why is ascending some stairs more exhausting than descending?
I have been asked this question by school kids, colleagues and family (usually less formally):
When ascending a flight of stairs, you exchange mechanical work to attain potential Energy ($W_\text{...
- 831
1
vote
1
answer
3k
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experiencing vibration when in contact with my desk computer and a rubbing a friend's arm [closed]
I was with a friend sitting next to my desk computer, I put my hand on the computer and the other one on my friend who is in contact with the floor. The thing is that when I rub my hand on his arm we ...
- 41
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0
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48
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Do prescription glasses augment or mitigate the effect of the sun on the skin around the eyes directly beneath them (assuming no UV blocking coating)?
The question is about minus correction (nearsightedness), but would also be interesting to know how it differs for plus correction (farsightedness), cylinder correction (astigmatism), axis correction.
- 39
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0
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58
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How much heat do we lose perspirating?
How can I calculate the heat my body loses from perspirating? For example, X Jouls per liter of sweat.
- 151
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4
answers
6k
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How can we feel temperature?
Recently I watched a Youtube Video by
Veritasium
He said we are actually feeling the rate of heat transfer, not the temperature.
But how do we feel temperature?
How is temperature different from ...
2
votes
3
answers
1k
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Why are ski jumpers slim?
Assuming perfect technique and material, how does the mass of a ski jumper affect the performance?
The higher potential energy of heavier jumpers could favour heavier jumpers, but then also friction ...
- 4,292
19
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5
answers
7k
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How is it possible for other animals to have better night vision than humans, who can detect individual photons?
According to the Wikipedia article on night vision,
Many animals have better night vision than humans do, the result of one or more differences in the morphology and anatomy of their eyes. These ...
- 48.4k
0
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1
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334
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Are noise cancelling headsets safe? [closed]
Older microlight headsets such as the Lynx Micro System are modelled on ear defenders and physically attenuate the noisy cockpit environment by clamping hard onto your noggin. Most modern GA headsets (...
- 119
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0
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264
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What are the possible dangers of removing the microwave shielding?
Would removing the shielding from a domestic microwave door allow the microwaves to cause damage to a consumer grade video camera, and if so, what damage would it cause?
- 183
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1
answer
685
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Electric discharge through my knuckle
In some particular days, it seems that my car is somehow at a different potential from the ground. When I get out my car and I wear my sneakers (that I think are better insulators than other kind of ...
- 1,764
4
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5
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2k
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Why is it so much easier to fall when walking down a slope?
When I walk uphill on an icey road, I almost never slip/fall. But if I walk downhill or even on a relatively flat road, I slip/fall frequently.
What is the physics reason behind this, and are there ...
- 57
18
votes
3
answers
10k
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Which requires more energy: walking 1 km or cycling 1 km at the same speed? [closed]
I feel more tired walking 1 km than cycling 1 km at the same speed. However when cycling I am moving the extra weight of the cycle along!
- 933
0
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2
answers
601
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Stability on a bus
I ride the bus from home to school and vice versa approximately 3-4 times per week for an hour each time. The bus is either bi- or tri-articulated, and it can accelerate to speeds up to 80km/h.
Most ...
3
votes
1
answer
5k
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How does eating a cold ice cream actually heat up your body? [closed]
The question is the title itself. During winter one of my friend told we'll have an ice cream. And rest of us where like are you nuts. He was like cold ice-cream actually heats up your body.
Even I ...
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3
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1
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11k
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Raising a cut on your arm above your heart
I often read that when you have a deep cut on your arm, you should raise your arm to the point where the cut is above your heart. This should reduce the amount of blood loss because less blood reaches ...
- 2,943
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3
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How do Calories (kcal) relate to watts?
In thinking about exercise and "burning calories" it occurred to me that there should be some fairly intuitive correlation between the biological energy conversion going on in a person's body with the ...
- 119
1
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5
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Lifting and putting down a weight
A man in a gym lifts a weight and then puts it down where it was before.
What can be said about the work done by the man to the weight?
Can it be equal in absolute value to the work made by the ...
- 673
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3
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5k
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Why can you lift more weight with bad form?
Sorry for the lack of academia behind the subject of the question, however I'm trying to prove a friend wrong.
He says that bad form with a deadlift will not allow you do more weight and he's doing ...
1
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0
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95
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How does it takes to deadlift a sports car? [duplicate]
In the movie Furious 7, Dom lift a Lykan HyperSport with bare hands.
Given that in reality, how strong it has to be to lift a Lykan HyperSport(1,380 kg), says to 40 cm in one rear end, and hold it ...
- 111
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1
answer
84
views
Plausibility of the distance estimation in a cycle ergometer gym exercise
A friend of mine pedaled for an hour on a cycle ergometer, a stationary bicycle in a gym.
At the end of the ride the cycle computer reported a distance of $40\:\mathrm{km}$ and an average power of $...
0
votes
3
answers
315
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?
user60881
8
votes
1
answer
14k
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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 ...
- 8,150
1
vote
2
answers
474
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What's Optimal About Six Legs According to Physical Laws? [closed]
In many respects the insects can be regarded as the most successful class of animals in evolutionary terms. And one of the most common features of insects is that they (mostly) all have six legs.
Not ...
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2
votes
0
answers
257
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Is WiFi safe for humans? [closed]
I have WiFi on at my home almost all the time. I learned that the frequency of visible light is around several hundreds of THz, while the frequency of wifi is only several GHz, which is only 1:100,000....
- 139
23
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4
answers
108k
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How much energy in form of heat does a human body emit?
How much energy in form of heat does a human body emit at rest level?
- 343
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votes
2
answers
977
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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 ...
- 17.1k
3
votes
2
answers
255
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 ...
- 2,905
-4
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3
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3k
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Life and Death, and Energy Conservation
Humans are born and they die. When we are born, is energy created? Or is it just some amount of energy that our mother gives us? Doesnt she take this energy from the surroundings? If so, then when we ...
- 1,128
3
votes
3
answers
996
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 ...
- 2,905
5
votes
1
answer
2k
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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 ...
- 1,575
3
votes
1
answer
202
views
Why do beverages taste different based on how cold they are? [closed]
Why does temperature effect the taste of beverages?
Specifically, how does the temperature for example mask certain tastes ie filtered vs unfiltered water taste very similar at colder temp and Is ...
- 1,241
2
votes
3
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6k
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Why the pressure of atmosphere doesn't crush you when you e.g. walk outside?
Why the pressure of atmosphere doesn't crush you when you e.g. walk outside? I mean the density of air is $1.26 kg/m^3$, so with $100 km$ above us, it exerts much pressure on you when you walk outside....
- 735