Question

A diagram labeled Before Collision shows two train cars moving toward each other. 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 negative 2 meters per second. A second drawing labeled After Collision shows two train cars moving away from each other.
Consider a system to be two train cars traveling toward each other.

What is the total momentum of the system before the train cars collide?


kg •

What must the total momentum of the system be after the train cars collide?


kg •

Answer 1

Total momentum before = 600(4) + 400(−2) = 2400 − 800 = 1600 kg·m/s (to the right).

Total momentum after = 1600 kg·m/s (momentum is conserved).