Three identical boxcars are coupled together and are moving at a constant speed of 28.0 on a level, frictionless track. They collide with another identical boxcar that is initially at rest and couple to it, so that the four cars roll on as a unit. Friction is small enough to be neglected.
Part A What is the speed of the four cars?
Part B What percentage of the kinetic energy of the boxcars is dissipated in the collision?
Part C What happened to this energy?