1. A railroad car of mass 28400kg moving at 2.33 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 1.06 m/s. What is the speed of the three coupled cars after the collision? Answer in units of m/s 2. m1v1i +m2v2i = (m1 +m2) Vf 3. I thought that since this is an inelastic collision, once the three rail road cars stuck together, their final velocity would be the same. So using the equation above, and solving for Vf : 28400 kg (2.33 m/s) + 2x 28400 kg (1.06 m/s) = ( 85200 kg) Vf 66172 + 60208 = 85200 Vf Vf= 0.7767 m/s But this isn't correct = ( Any help please?