1. Calculate the force needed to pull a mass of 20 kg at a uniform speed up a plane inclined at an angle of 30° with the horizontal if the coefficient of kinetic friction is 0.20.
2. Suppose the force in above question is a push applied horizontally on the mass instead of a pull directed parallel to the plane.
a) Calculate the value this force must have to keep the mass moving up the plane at constant speed.
b) Is there an angle other than 90° for the plane at which no horizontal force can keep the mass moving at constant speed? If so, what is it?