A railroad car of mass 2.7 104 kg moving at 3.50 m/s collides and couples with two coupled railroad cars, each of the same mass as the single car and moving in the same direction at 1.20 m/s.

Question

A railroad car of mass 2.7  104 kg moving at 3.50 m/s collides and couples with two coupled railroad cars, each of the same mass as the single car and moving in the same direction at 1.20 m/s.
(a) What is the speed of the three coupled cars after the collision?
  m/s

(b) How much kinetic energy is lost in the collision?
  J

bobpursley · Answer

a. conservation of momentum intial=final M*3.5+2M*1.2=3M V solve for V b. intial KE=1/2 M 3.5^2+ M 1.2^2 final KE=3/2 M V^2 lost is the difference

John · Answer

3 meters per second