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A amn rowing a boat upstream is at rest ...

A amn rowing a boat upstream is at rest with respect to shore. (a) Is he doing any work ? (b) If he stope rowing and moves down with the stream, is any work being done on him ?

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(a) No work is being done by the net force because displacement of boat relative to the shore is zero.
(b) When he stops rowing, force of water flow will produce displacement w.r.t the shore. Therefore, work is doen by force of flowing water. KE of the person will increase.
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