Question

A block of mass m lies on a wedge of mass M. The wedge in turn lies on a smooth horizontal surface. Friction is absent everywhere. The wedge-block system is released from rest. All situations given in Column I are to be estimated in duration the block undergoes a vertical displacement h starting from rest. Match the statements in Column I with the results in Column II. (g is acceleration due to gravity.)

Answer 1

$\ast$ Work done by normal reaction is zero because Normal reaction is perpendicular to force.

($w=F\cos \theta .S=0$)

$\ast$ Work done by normal reaction (exerted by block) acting on the wedge is positive because wedge will move in the same direction in which normal force will act so that backward direction.

$\ast$ the sum of work done by normal reaction is zero because external force is not present and no work in done is absence of external force work done is zero.

$\ast$ Net work done by all the forces on the block is positive because block will move in the same direction in which net forces acts on the block.