A Railway Boxcar Is Moving Toward a Stationary Boxcar on a Rail

Multiple Choice

A railway boxcar is moving toward a stationary boxcar on a rail with negligible friction. The stationary boxcar is twice the mass of the moving one. On collision, the boxcars couple to each other. After the collision, what is the velocity of the more massive boxcar? Express your answer as a fraction of the velocity of the less massive boxcar before the collision.

A) 1/2
B) 1/3
C) -1/3
D) -1/2