Question

12,000kg. railroad car is traveling at 2m/s when it strikes another 10,000kg.railroad
car that is at rest. If the cars lock together, what is the final speed of the two railroad cars?

Answer 1

Answer:

1.091 m/s

Theory

The law of conservation of linear momentum

The sum of linear momentum of a system under no external force remains constant.

In this scenario although different forces act on two vehicles by each other when we consider the total system of two cars no external unbalance force act on them. So we can apply this law.

As law says,

The sum of linear momentum before collision = The sum of linear momentum after collision.

Momentum = mass × velocity.

So we get, 12000×2 +10000×0 = 22000×v where v = velocity of the locked cars,

v = 1.091 ms⁻¹