A railroad freight car weighing 280kN and traveling at 1.52 m/s overtakes one weighing 210kN and traveling at 0.914 m/s in the same direction. If the cars couple together, find

(a) The speed of the cars after the collision and

(b) The loss of kinetic energy during the collision. If instead, as is very unlikely, the collision is elastic, find the after-collision speed of

(c) The lighter car and

(d) The heavier car.