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If we could assume:

  • We don't increase our energy from absorbing food.
  • Our human example in scope isn't starving or suffering from malnutrition.

I mean how much work can we do until the body would die from exhaustion.

Sometimes when we work out, we have this sudden 'burst' of energy. Where does this energy come from, and how long, biologically are we capable of converting this energy to the various forms of energy we expel from our bodies: heat, mechanical, etc..

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closed as off-topic by joseph f. johnson, HDE 226868, Gert, user36790, DilithiumMatrix Nov 29 '15 at 2:25

  • This question does not appear to be about physics within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ I think you need to be more specific. There are many different kinds of "potential energy" and stating the question in this manner is very open ended... $\endgroup$ – honeste_vivere Nov 28 '15 at 22:04
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    $\begingroup$ Hi, this isn't the usual meaning of the word "potential energy" (because you're talking about useful work). I think it would help if you changed your title to "How much work can the human body do before dying of exhaustion", since that's the real question. $\endgroup$ – user12029 Nov 28 '15 at 22:13
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    $\begingroup$ This is probably more biochemistry than physics. $\endgroup$ – Kyle Kanos Nov 28 '15 at 23:19
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    $\begingroup$ I'm voting to close this question as off-topic because it is primarily about biology. $\endgroup$ – HDE 226868 Nov 29 '15 at 0:54
  • $\begingroup$ I don't find this question off-topic, it is well within the tag "biophysics". $\endgroup$ – scrx2 Nov 29 '15 at 6:36
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What is the potential energy of the human body?

36 MJ $\simeq$ 8600 kcal.

The basal metabolic state for a human is about 60 W. Let's assume (horrible) an immobile person dies after one week (604800 s) of starvation, he will have consumed 60 W * 604800 s = 36,288,000 J.

Where does this energy come from?

from the high energy chemical bonds of complex molecules we eat (and light for plants), which are gradually and sequentially oxydized in a controlled way by a set of enzymes. (some background: The energy released in each step in their degradation is used during cellular respiration by other processes, in particular ion pumps, that eventually produce a voltage difference in mithocondria. This $\Delta V$ is eventually used by a tiny nanometer rotary motor (F0F1) to produce ATP, the molecule consumed in a immense variety of processes, including mechanical muscle contraction.)

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