A boy tied a string to one of the ends of a box and started sliding the box on a playground. He then observed a circular track and rushed there and completed one revolution of the track with his toy. The work done by friction on the toy is
Non- zero
The work done by friction depends upon the actual length of the path traversed and it is not zero. It is dissipative in nature, so even in the question above, the displacement is zero but the work done by friction would be non-zero and energy is dissipated as heat into the surroundings.