A small box of mass m1 is sitting on a board of mass m2 and length l (figure 1). The board rests on a frictionless horizontal surface. The coefficient of static friction between the board and the box is μs. The coefficient of kinetic friction between the board and the box is, as usual, less than μs. Throughout the problem, use g for the magnitude of the acceleration due to gravity. In the hints, use ff for the magnitude of the friction force between the board and the box.