A train car has a mass of 10,000 kg and is moving at + 3.0 m/s. It strikes an identical train car that is at rest. The train cars combine. A train car has a mass of 10,000 kg and is moving at + 3.0 m/s. It strikes an identical train car that is at rest. The train cars combine. What is the magnitude of the final velocity of the combined cars?

In order to compute the final velocity of the trains, we may apply the principle of conservation of momentum which is:

initial momentum = final momentum

m₁v₁ = m₂v₂

The final mass of the trains will be:

10,000 + 10,000 = 20,000 kg

Substituting the values into the equation:

10,000 * 3 = 20,000 * v

v = 1.5 m/s

The final velocity of the trains will be 1.5 m/s