A 120-lb cabinet is mounted on casters that can be locked to prevent their rotation. The coefficient of static friction between the floor and each caster is 0.30. If h = 32 in., determine the magnitude of the force P required to move the cabinet to the right (a) if all casters are locked,
(b) if the casters at B are locked and the casters at A are free to rotate,
(c) if the casters at A are locked and the casters at B are free to rotate.