In the railroad freight yard, an empty freight car of mass m rolls along a straight level track at 1.0 m/s and collides with an initially stationary, fully loaded boxcar of mass 3.8m. The two cars couple together upon collision. (a) What is the speed of the two cars after the collision? This is the equation I have devised so far: m1= M m2= 3.8m V1= 1.0 m/s p2= 0 pf=p1 or (m1 + m2 )vf = (m1v1) Vf = (m1)(1.0) / (m1 + 3.8) I don't think this is correct. With the first mass being indicate as only m, I'm not sure how to compensate. Could someone please let me know what I'm doing incorrectly?