Two 425,000-lb locomotives pull 50 200,000-lb coal hoppers. The train starts from rest a...

Two 425,000-lb locomotives pull 50 200,000-lb coal hoppers. The train starts from rest and accelerates uniformly to a speed of 40 mi/hr over a distance of 8000 ft on a level track. The constant rolling resistance of each car is 0.005 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 20 mi/hr, (b) the power required from each locomotive at 20 mi/hr, (c) the power required from each locomotive as the train speed approaches 40 mi/hr, and (d) the power required from each locomotive if the train cruises at a steady 40 mi/hr.