ThermoD

A 100kg block is started with a speed of 2m/s on a long, rough belt kept fixed in a horizontal position.
The coefficient of kinetic friction betn. the block and the belt is 0.20.

Consider the situation from a frame of reference moving at 2 m/s along the initial velocity of the block. As seen from this frame, the block is gently put on a moving belt and in due time the block starts moving with the belt at 2m/s. Find the work done in this frame by the external force holding the belt.