1. The problem statement, all variables and given/known data This has had me puzzled for a few hours now, Its about forces acting down a plane. Q. A car of a mass (m) is travelling with a constant velocity up a hill at an angle (any angle - theta ) to the horizontal as indicated If F is the resultant force acting on the car, the effective engine force needed to maintain this consant velocity must be A = mgcos(theta) + F B = mgcos(theta) - F C = mgsin(theta) + F D = mgsin(theta) - F E = mg + Fsin(theta) Any help will be apprieciated My work I tried making up values for the equations. It worked but it didnt really match the equations matched in the answer. Fh = fcos(theta) Horizontal Force Fv = fsin(theta) Vertical Force As its horizontal I have igonred the answers with sin. But I somehow dont know why it either has to be plus or minus F. Would that not equal an unbalanced force.