Question

 In which case work is not done?​

Answer 1

Answer:

Let us consider some cases where work is not done:

Work is zero if applied force is zero (W=0 if F=0): If a block is moving on a smooth horizontal surface (frictionless), no work will be done. Note that the block may have large displacement but no work gets done. Work is zero if Cos θ is zero or θ = Π/2.