1. The problem statement, all variables and given/known data a frictionless roller coaster car of mass m = 954 kg tops the first hill with speed v0 = 24.2 m/s at height h = 30.8 m. How much work does the gravitational force do on the car from that point to (a) point A. (same height) 2. Relevant equations 3. The attempt at a solution One question is baffling me, do I need to include kinetic energy when calculating using the change of gravitational potential energy? Does it mean that question (a), work does by the gravitational force is zero ?