?? railroad car doesnt make sense... here goes... A railroad car of weight W can roll without friction along a straight horizontal track. A man od weight w is standing on the acr which is moving at a speed of V1. Prove that change in v = w(v1 + Vrel)/W if Vrel is the speed of the man moving off the left end relative to the car. (car is going right, man is going left) thanks!