A 11600 kg railroad car is coasting on a level, frictionless track at a speed of 16.0 m/s when a 5420 kg load is dropped onto it. If the load is initially at rest, find the new speed of the car and the % change of the kinetic energy.

The speed of the car when load is dropped in it is 10.90 m/s.

Explanation:

Given that,

Mass of the railroad car, m₁ =  11600kg

Mass of the load, m₂ =  5420kg

It can be assumed as the speed of the car, u₁ = 16 m/s

Initially, it is at rest, u₂ = 0

The additional load is dropped onto the car.

Let v is the speed of the car. It can be calculated using the conservation of momentum as :

So, the speed of the car when load is dropped in it is 10.90 m/s.

option number c is the right answer.