In the railroad freight yard, an empty freight car of mass m rolls along a straight level track at 1.30 m/s and collides withan initially stationary,fully loaded boxcar of mass 4.70m.The two cars couple together on collision. -What is the speed of the two cars after the collision? -Supposeinstead that the two cars are at rest after the collision. With what speed was the loaded boxcar moving before the collision if the empty one was moving at 1.30 m/s?