- #1
khan
- 5
- 0
Let's say I am strong enough to lift a 100 kg dumbbell, but not strong enough for a 200 kg one.
If I lift the 100 kg dumbbell, I suppose the chemical energy of my body tranforms into the potential energy of the lifted dumbbell. Suppose I'm trying to lift the 200 kg one. I'm pulling as hard as I would be if I were lifting the 100 kg one, so the loss of my energy should be the same. But the dumbbell stays on the ground so there is no gain in its potential energy. My question is, where does my energy go? It seems to me that on my part, nothing changes, I'm pulling as hard as I can in both cases, sweating, pressing the floor, whatever. So what accounts for the difference in the change of potential energy in the case of the lighter dumbbell and no change of potential energy in the case of the heavier one?
If I lift the 100 kg dumbbell, I suppose the chemical energy of my body tranforms into the potential energy of the lifted dumbbell. Suppose I'm trying to lift the 200 kg one. I'm pulling as hard as I would be if I were lifting the 100 kg one, so the loss of my energy should be the same. But the dumbbell stays on the ground so there is no gain in its potential energy. My question is, where does my energy go? It seems to me that on my part, nothing changes, I'm pulling as hard as I can in both cases, sweating, pressing the floor, whatever. So what accounts for the difference in the change of potential energy in the case of the lighter dumbbell and no change of potential energy in the case of the heavier one?