A locomotive accelerates a 25-car train along a level track. Every car has a mass of 7.6 ? 104 kg and is subject to a friction force f = 250v where the speed v is in meters per second and the force f is in newtons. At the instant when the speed of the train is 33 km/h, the magnitude of the acceleration is 0.20 m/s2.
(a) What is the tension in the coupling between the first car and the locomotive?
N
(b) If the tension is equal to the maximum force the locomotive can exert on the train, what is the steepest grade up which the locomotive can pull the train at 33km/h?
°