posted by Priyanka .
In the railroad freight yard, an empty freight car of mass m rolls along a straight level track at 1.1 m/s and collides with an initially stationary, fully loaded boxcar of mass 4.3m. The two cars couple together upon collision.
(a) What is the speed of the two cars after the collision?
I believe it's m1(v1)+4.3(1.1)/m1+4.3 but i don't know what m1 and v1 would be?