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This has always puzzled me. As i stand on the earth i require energy to exert a force over gravity to enable me to keep standing. The net force between me and the the earth is zero and thus i remain standing still. However my amount of energy depletes as a result of this and will culminate in me being unable to stand as a result of the energy loss. Where does the energy for the earth come in order to apply the force of gravity between me and it. Since i appear to suffer a loss of energy what happens with respect to the earth exerting a force over me.

Qmechanic
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8Mad0Manc8
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    However my amount of energy depleats as a result of this and will culminate in me being unable to stand as a result of the energy loss. No, it doesn't. – HDE 226868 Apr 21 '15 at 22:39
  • Think of an inanimate object, a flower pot, a chair. It would sit there forever, no energy is exchanged or is necessary to sit there forever. – anna v Apr 22 '15 at 05:38
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    Related: http://physics.stackexchange.com/q/1984/ – HDE 226868 Apr 22 '15 at 17:57
  • @anna v Yes the plant does not be come tired over exertion of repelling the pull of the earth but we still become tired when stood up there is not movement and as such no work done or loss in energy or transference occurs that we could measure however when we stand up our body gains potential energy as it center of gravity is above the surface of the earth we can measure the exertion this movement ocurrs as work done = gains in potential energy but why do we feel tired when we maintain the potential energy our bodies have gained. – 8Mad0Manc8 Sep 17 '16 at 20:53
  • You feel tired because you are not a flower pot. The biological organism has to spend energy to keep the position you have: people fainting fall, which means that to maintain a "solidity of flower pot" for the body, is being spent, i.e calories will be burned and all the biological cycle of "tired" will appear after a while. – anna v Sep 18 '16 at 03:44
  • @anna v Yes but what if I want to be a flower pot? is this something I cannot ever ever achieve and a such I am simply only able to pretend to be a flower pot. – 8Mad0Manc8 Sep 18 '16 at 10:37
  • @anna v sorry for my silliness but it represents a question that is not covered in your answer. Of course a plantpot or any other stable thing i cant answer for my mind however lol. There is no exertion in that body and simply opposes the force of gravity upon it has not an exertion of force over a distance and therfore no energy is transferred. I can imagine that our bodies acompany the stiffness and what is necessary to keep us in this position. Maybee i have not grasped this concept but it still puzzles me no end. – 8Mad0Manc8 Sep 24 '16 at 20:12

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I advise you to go lie down. Go on, do it. Put your back to the ground and just lie there. After a while you'll notice that you don't feel any weaker. Why? Because you haven't lost any energy.

It takes no energy to resist another force. It does take energy to apply a non-zero force to an object to do work: $$W=F\cos\theta s$$ Or, for a variable force. $$W= \int F ds$$ where $W$ is work (in units of Joules, just like energy), $F$ is force, $\theta$ is the angle between the force and the displacement, and $s$ is the displacement (with $ds$ being an infinitesimal displacement). But while you're lying down, your displacement, $s$, is zero. This means that $$W=F\cos\theta\times(0)=0 \text{ Joules}$$ It takes no energy to do no work, which, in this case, is applying a force over zero distance.

On a different note, while you're lying down (or standing up), the forces between your feet and the ground are gravity and the electromagnetic force. The electromagnetic force means that when you're standing on the ground, the atoms in your feet aren't actually touching the atoms in the ground. So you're not even the thing applying force!

HDE 226868
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The energy doesn't deplete. Sometimes it helps to think of gravity as curved space-time. That visualization might help.

Jimmy360
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