1. The problem statement, all variables and given/known data A roller coaster car has a mass of 800kg. It is released from the top of the hill A and moves without friction down the track. Determine the minimum exit velocity vD at ground level so that the car travels around both the circular loops (Loop B - Radius= 10m, Loop C - Radius= 7m) without leaving the track. Diagram here, http://i284.photobucket.com/albums/ll12/uradnky/rc.jpg" [Broken] 3. The attempt at a solution To do this I thought that I would just use basic conservation of energy and trace the velocity of the roller coaster through both of the loops untill it exits. In this problem the height isn't given, and must be calculated in another part of the problem. Without knowning the height that the coaster begins at, how would I begin?