Problem
In the railroad freight yard, an empty freight car of massm rolls along a straight level track at 1.2 m/s and collides with an initially stationary, fully loaded boxcar of mass 4.30m. The two cars couple together upon collision.
1. What is the speed of the two cars after the collision? ___m/s
2. Suppose instead that the two cars are at rest after thecollision. With what speed was the loaded boxcar moving before thecollision if the empty one was moving at 1.20 m/s? ___m/s