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Question
A body of mass m falls down through a height h. Obtain an expression for the work done by the force of gravity.
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Solution
Assume that a body A with mass'm' is elevated 'h' above the ground, and B falls.
Force acting on 'm' at A is mg force of gravity.
Displacement = height = h
Work done in falling W = force × displacement
W = mg × h
The formula for the amount of work that gravity has done is W = mgh.
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