1. The problem statement, all variables and given/known data Two freight trains have a completely inelastic collision at a track crossing. Engine 1 has a mass of 1.4x10^4 kg and is initially travelling at 45 km/h [N]. Engine 2 has a mass of 1.5x10^4 kg and is initially travelling at 53 km/h [W]. Calculate the final velocity. 2. Relevant equations 3. The attempt at a solution p^2=p1^2+ p2^2 =(1.4x10^4)(12.5m/s)^2+ (1.5x10^4)(14.72m/s)^2 =281740m/s The answer in the textbook is 9.7m/s. What am I doing wrong?