It is tiring because I'm slowing my descent. If I just fell from the stairs the potential energy I would loose would got to my kinetic energy and then to the vibrations of the floor. If I'm walking down I move more slowly and don't stomp so much, so some of the potential energy I loose somehow...
Thanks, these are great examples!
So you think that my muscles are heated more if I'm trying to lift the weight but am not able to? That would explain where the energy goes. But it would also mean that the more work you do, the less you sweat :) It makes sense, but still seems weird...
I'm not sure if I understand you. Are you trying to say that the energy that would go into lifting the weight goes instead into heating my muscles? So my muscles are heating more if I'm not unable to lift the weight? That would explain where the energy goes to, but seems quite unintuitive...
And...
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...