Recap - Roller Coaster

A $500\ \mathrm{kg}$ roller coaster car waits at rest on the flat top of a $30\ \mathrm{m}$ hill, then leaves it. It races down into a valley and climbs over a second hill $20\ \mathrm{m}$ high. The track has no friction. The picture shows the car twice: on the first top and on the second. Draw the forces on it while it waits on the first top, then find the speed $v$ of the car at the top of the second hill.