Thanks, Bill, I'm always on the lookout for someone to do some thinking for me. smile

Quote:
GPE is really the amount of energy that the object can gain in falling to the Earth.


This is more or less how I thought of it until I started reading PS books, and, even worse, thinking about what I read.

Looking back through my notes, I find myself arguing that the GPE of (eg) a stone resting on a shelf 3m above the ground cannot simply be the result of my having picked it up and placed it there, because if I dig a pit under the shelf then push the stone off, it will fall to the bottom of the pit.

Thinking along these lines did bring me to a sort of conclusion, but I'm going to find my notes, and see if they still make sense to me before say anything I might regret.

There never was nothing.