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If energy is movement, how come I get tired just from holding a heavy object? (multiverse.soulism.net)
submitted 1 month ago by to c/nostupidquestions@lemmy.ca
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In high school physics, I learned that the equation for energy from moving something is a factor of force and displacement. So if an object remains stationary, then no matter how much force is put into it, no energy is expended.

So how come if I hold a heavy box filled with dumbbells, I get tired? I'm obviously putting a lot of newtons into it to keep it from falling, but it's not moving. So how is the weight of the object causing Me to expend energy?

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[โ€“] [S] 2 points 1 month ago (1 child)

Huh. So if I expend the same amount of energy lifting a light object and holding a heavy object, I'll get hotter when holding the heavy one?

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  • [โ€“] 3 points 1 month ago

    In principle, yes. In the lifting scenario, a portion of the work done by your body becomes potential energy of the weight, so only some behind waste heat. In the holding-up scenario, all of the energy becomes waste heat.

    In practice, though, I don't see how you'd know exactly when to stop in order to meet the "same amount spent" condition.

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