1. The problem statement, all variables and given/known data A 1550-kg car experiences a combined force of air resistance and friction that has the same magnitude whether the car goes up or down a hill at 21 m/s. Going up a hill, the car's engine produces 44 hp more power to sustain the constant velocity than it does going down the same hill. At what angle is the hill inclined above the horizontal? 2. Relevant equations P=W/t=FvCosθ W=fΔx 3. The attempt at a solution I drew out my free body diagram and I have the Normal force, friction, and the components of the weight force (mgCosθ in the y-direction and mgSinθ in the x-direction) I figured I need to find out the F in P=FvCosθ. I'm just not sure what F it is I have to find.