A block of mass m slides down a frictionless wedge of mass M which itself rests on a smooth horizontal surface. During a vertical descent h of the block, match the work/energy statements.

Question

G1 Physics · Accepted Answer

Let the block descend vertically by h. Gravity does +mgh work on the block. Because the wedge also acquires kinetic energy, the block receives less than mgh as net work; hence the block's net work is positive and less than mgh: D→P,S. For the wedge, the only force doing horizontal work is the normal force exerted by the block, so its work equals the positive kinetic energy gained by the wedge and is less than mgh: B→P,S. For the block, W(net)=W(g)+W(N). Since 0<W(net)<mgh, W(N)=W(net)-mgh…