A railroad car of mass 2.44 104 kg, is moving with a speed of 3.96 m/s. It collides and couples with three other coupled railroad cars, each of the same mass as the single car and moving in the same direction with an initial speed of 1.98 m/s.
(a) What is the speed of the four cars after the collision?
(b) How much energy is transformed into heat, light and sound in the collision?