A 7760-kg rollercoaster is moving at 3.00 m/s as it rolls over the top of a hill that is 40.0 m tall.
a) How fast is it moving when it reaches the bottom of the first hill, which is at ground level?
b) How fast is it moving as it rolls over the next hill that is 30.0 m above ground level?
c) Assume there is no friction.