Question

You push a heavy crate. At first it doesn't move. You push harder, and it finally starts to move, but you still have to exert some force to keep it moving at a constant velocity. Explain.

Answer 1

At first you had to exert a large force to overcome static friction. After the crate started to move, you still had to exert a smaller force to overcome sliding friction.

Answer 2

Thank you so much !

Answer 3

anytime!