12 N (c) F = 12 N and directed 30 degree above horizontal , m = 1.0 kg. 5. Starting from rest a box of mass 2 kg slides down 30 degree inclined plane. The coefficient of kinetic friction between the plane and the box is 0.2. (a) Determine the work done by all forces acting on the box. 6 m (b) What is the speed of the box at the bottom of the plane? (c) What will be the speed at the bottom if the plane is frictionless