physics .
posted by maria on .
A roller coaster starts from rest 85m above the ground . Assume there is no energy lost when it reaches the top of the secound hill , which is 55m high. How fast is the tolerant coaster moving?

The potential energy loss equals the kinetic energy gain. The mass will cancel out and you will be left with
g*(85  55) = V^2/2
Solve for V