Physics
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.
Work, Energy & Power
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Answer
(a) A man pushes a wall.— No
Reason: There is no displacement of the wall, so no work is done.
(b) A coolie stands with a box on his head for 15 minutes. — No.
Reason: The coolie is not moving, so there is no displacement.
(c) A boy climbs up 20 stairs. — Yes
Reason: There is displacement in the direction of force (against gravity), so work is done.
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