A block of mass 'm', kept on a horizontal surface, is moved through a distance 's' by applying a horizontal force (F) to it. What is the work done by the normal reaction?

Step-by-step solution

In the first case, the centre of gravity is at a height = b 2 Work done = mgh = mg ( b 2 ) In the second case, the height of the centre of gravity = L 2 Work done =m g L 2 L>b Extra work done =m g ( L-b 2 )