Question 10: A man rowing boat upstream is at rest with respect to shore. Is he doing work? ANSWER Physically, work is done when a certain force is applied to some body and causes motion in it.
Work = .=FdcosΘWhere is the force acting on the body and is the displacement covered as a result of this force. When the man is rowing the boat upstream but he is at rest with respect to the shore, he is not covering any displacement. Hence, putting = 0 in the above equation; work done = 0. Hence the man does not do any work when he is at rest with respect to the shore. The force the man exerted goes to balance the downstream push of the water.