All Questions
Tagged with everyday-life biophysics
52
questions
182
votes
14
answers
77k
views
Why does holding something up cost energy while no work is being done?
I read the definition of work as
$$W ~=~ \vec{F} \cdot \vec{d}$$
$$\text{ Work = (Force) $\cdot$ (Distance)}.$$
If a book is there on the table, no work is done as no distance is covered. If I ...
- 5,377
67
votes
15
answers
22k
views
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
33
votes
11
answers
12k
views
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
29
votes
10
answers
10k
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 ...
aaron
23
votes
4
answers
108k
views
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
19
votes
5
answers
7k
views
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
18
votes
3
answers
10k
views
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
8
votes
11
answers
1k
views
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
8
votes
1
answer
14k
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 ...
- 8,150
5
votes
3
answers
377
views
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'...
- 12.5k
5
votes
2
answers
6k
views
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
5
votes
1
answer
2k
views
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
4
votes
5
answers
2k
views
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
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
3
votes
2
answers
475
views
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 ...
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