1. The problem statement, all variables and given/known data Driving an automobile down a slippery, steep hill, a driver brakes and skids at a constant speed for 10m. If the automobile mass is 1700kg and the angle of the slope of the hill is 25 degrees, how much work does gravity do on the car during the skid? How much work does friction do on the car? 2. Relevant equations ΣFx = 0 Wx = -mgsinΘ Ff = ? Ff - Wx = 0 ΣFy = 0 Wy = -mgcosΘ N = mgcosΘ N - Wy = 0 3. The attempt at a solution Ff - Wx = 0 Ff = Wx Ff = -mgsinΘ Ff = -(1700kg)(9.81m/s2)sin25° Ff = -7.06x103N It seems to me that if Ff is -7.06x103N then the gravitational pull down the hill would have to be an equal but opposite 7.06x103N, but I am unsure about this. W = Fs cosΘ Wg = 7.06x103N cos25° = 6.4x10 3J Wf = -7.06x103N cos25° = 6.4x10 3J I know that this is an incorrect answer, however, I am unsure of what to do.