Question

A rough inclined plane is placed on a cart moving with a constant velocity u on horizontal ground. A block of mass M rests on the incline. Is any work done by force of friction between the block and incline? Is there then a dissipation of energy?

Answer 1

Let us consider the diagram according to the situation. Just imagine the situation the wedge is moving with velocity u. As the block Mis at rest with respect to the inclined plane. There is no pseudo force acting on the block because the wedge is moving with constant velocity. So, f = frictional force = Mg sinθ (upward as shown in the figure)

As the block rests on the incline, the force of friction acting between the block and the incline opposes the tendency of sliding the block. Since the block is not in motion with respect to the incline, therefore, work done by the force of friction between the block and the inclined plane is zero. Also due to this reason, there is no dissipation of energy.