Is gravity endless energy?

Question

You need energy to produce a force that compensates gravity. So if you apply that force for a huge amount of time, will gravity ever be depleted?

In: 39

Answer 1

So in order for a book to rest on a table and not move relative to the Earth, the table needs to exert a force on this book. It’s called the normal force. Where is this energy coming from that this table is exerting on the book?