Question

A diagram labeled Before Collision shows two train cars with the one on the left moving toward the on on the right. The car on the left is labeled m Subscript 1 Baseline = 600 kilograms and v Subscript 1 Baseline 4 meters per second. The car on the right is labeled m Subscript 2 Baseline = 400 kilograms and v Subscript 2 Baseline 0 meters per second. A second drawing labeled After Collision shows two train cars stuck together and moving to the right.
Consider a system to be one train car moving toward another train car at rest. When the train cars collide, the two cars stick together.

What is the total momentum of the system after the collision?

800 kg •
1,600 kg •
2,400 kg •
4,000 kg •

Answer 1

Momentum is conserved. Initial momentum = 600 kg·4 m/s + 400 kg·0 = 2400 kg·m/s. So after the collision the total momentum is 2400 kg·m/s.