Question

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 0.300m/s, and the second having a mass of 110,000 kg and a velocity of -0.120m/s. (The minus indicates direction of motion.) What is their final velocity?

Answer 1

Answer:

0.122 m/s

Explanation:

mass of first train, m1 = 150,000 kg

initial velocity of first train, u1 = 0.3 m/s

mass of second train, m2 = 110,000 kg

initial velocity of second train, u2 = - 0.120 m/s

let the velocity of coupled mass after the collision is v.

Use the conservation of momentum

Momentum of trains before collision = Momentum of trains after collision

$m_{1}\times u_{1}+m_{2} \times u_{2}=(m_{1}+m_{2})v$

150000 x 0.3 - 110000 x 0.120 = (150000 + 110000)v

45000 - 13200 = 260000 v

31800 = 260000 v

v = 0.122 m/s

Thus, they travel with the speed of 0.122 m/s towards right after collision.