- #1

- 35

- 0

So if I lift a book from the ground it gains potential energy. I do work on the book and when I release it the potential energy that I gave the book pulls the book back down to Earth.

However I was looking at a potential energy formula for planets which was

V = -GMm/r

But this doesn't make sense because a) why is potential energy negative and b) why does the absolute value of it get smaller with increasing r? The potential energy should increase with increasing r (it does, but because I don't understand the negative sign I'm thinking of its absolute value).

Cheers