1. The problem statement, all variables and given/known data A roller coaster is just barely moving as it goes over the top of one hill. it rolls nearly frictionless down the hill and then up over a lower hill that has a radius of curvature 15m. How much higher must the first hill be than the second if the passengers are to exert no force on the seat as they pass over the top of the lower hill? 2. Relevant equations angular kinematic equations. 3. The attempt at a solution No idea where to start. Can someone give me a boost on how I should take this problem? Are there going to be real values or this is formula manipulation? I think if i use KE=PE I can get the velocity for a certain height no?