1. The problem statement, all variables and given/known data A force F is applied on a block of mass M.The block is displaced through a distance "d" in the direction of the force.What is the work done by the force on the block?Does the internal energy change because of this work? 2. Relevant equations 3. The attempt at a solution The work done by the force =Fd By Work Kinetic energy theorem ,change in kinetic energy of the CM of the block is =(1/2)mvcm2 The internal energy can change either by supplying heat to the system or by doing work on the system. Work is being done on the block .The KE of the CM of the block changes.But how does this work affects the internal energy of the block ? Kindly help me in clearing the doubt.