Two books are placed on a set of shelves. One is a 2-kg book that is placed on a 5-m high self, and the other is a 5-kg book placed on a 2-m high self. How do the books potential energies compare?

Question

A. The more massive book has more potential energy

B. The less massive book has more potential energy

C. The two books have the same potential energy

D. We can't tell without knowing the force acting on each book

Answer 1

U = potential energy

U = mgh

Since g is the same for both, all you need to do is find and compare mh for both books.

Book 1:

m₁h₁ = (2 kg)(5 m) = 10 kg-m

Book 2:

m₂h₂ = (5 kg)(2 m) = 10 kg-m

They have the same potential energy.