I need help with physics problem

Question

A car parked on the top of a 50 m hill slips out of gear and rolls down the icy hill. How fast is it going at the bottom of the hill? Friction can be neglected

Answer 1

With negligible friction, mechanical energy is conserved and transitions from all potential to all kinetic. At the top, ME_i = mgh = m(9.8)(50) = 490m. At bottom, ME_f = ME_i = 490m = (1/2)mv², so mass cancels, v² = 980, and v = 31.3 m/s.