Question

the most common reasons for rear - end collisions are too short a following distance, speeding and failing brakes. car A of mass 1000 kg, stationary at a traffic light, is hit from behind by car B of mass 1200kg, travelling at 18m.s. immediately after the collision car A moves forward at 12m.s
Assume that linear momentum is conserved during this collision. calculate the speed of car B immediately after the collision.

Answer 1

You have to know the movement of both cars after the collision, not just car A.