A block of mass M is tied to one end of a massless rope the other end of the rope is in the hands of a man of mass 2M as shown in the figure the block and the man are resting on a rough plank of mass M as shown in the figure the whole system is resting on a smooth horizontal surface the man pulls the rope pulley is massless and friction what is the displacement of the plank when the block meets the pulley ( Man does not leave his position on plank during the pull)