Conservation of Momentum (Problem 23)

Professional Application Train cars are coupled together by being bumped into one another. Suppose two loaded train cars are moving toward one another, the first having a mass of 150,000 kg and a velocity of 0.300 m/s, and the second having a mass of 110,000 kg and a velocity of $-0.\text{120 m/s}$. (The minus indicates direction of motion.) What is their final velocity?