State whether work is done or not by writing yes or no, in the following cases?

(a) A man pushes a wall.

(b) A coolie stands with a box on his head for 15 min.

(c) A boy climbs up 20 stairs.

Solutions:

(a) Work is done by a man

(b) No, work is not done by a coolie

(c) Yes, work is done by a little boy ascending a flight of stairs.