Give reasons for the following:
'No work is done when a person pushes against the strong wall.'
Give reasons for the following :
(a) No work is done if a man is pushing against a wall.
(b) The hammer drives a nail into the wood only when it is lifted up and then struck.
(c) A horse and a dog are running at the same speed. Which one of them has more kinetic energy than the other
(d) A teacher moving around in the class is doing work but a child standing and reading a book is not doing any work?
A person pushing a wall hard is liable to fall back. Give reason.
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.
No work is done if a person is pushing against a wall. give a reason for the same.
Is any work done when we push a wall with our hand?why?