Two 415,000-lb locomotives pull 41 205,000-lb coal hoppers. The train starts from rest and accelerates uniformly to a speed of 42 mi/hr over a distance of 9200 ft on a level track. The constant rolling resistance of each car is 0.007 times its weight. Neglect all other retarding forces and assume that each locomotive contributes equally to the tractive force. Determine (a) the tractive force exerted by each locomotive at 21 mi/hr, (b) the power required from each locomotive at 21 mi/hr, (c) the power required from each locomotive as the train speed approaches 42 mi/hr, and (d) the power required from each locomotive if the train cruises at a steady 42 mi/hr.