1. The problem statement, all variables and given/known data Part of a roller-coaster ride involves coasting down an incline and entering a loop 8.00 m in diameter. For safety considerations, the roller coaster speed at the top of the loop must be such that the force of the seat on a rider is equal in magnitude to the rider's weigt. From what height above the bottom of the loop must the roller coaster descend to satisfy this requirement? 2. Relevant equations a_c = v^2/r Conservation of Energy 3. The attempt at a solution m* a_c = mg m* v^2/r = mg v^2/r = g v^2 = rg mgh = 1/2 mv^2 + mg * 8 9.8 * h = 1/2 * rg + 8 * 9.8 9.8 * h = 1/2 * 4 * 9.8 + 8 * 9.8 h = 2 + 8 h = 10 However, the answer is 12. Please guide me to the solution. Thanks!