A gun is mounted on a stationary rail road car. The mass of the car, the gun, the shells and the operator is 50 m, where m is the mass of one shell. Two shells are fired one after the other along same horizontal line in same direction. If the muzzle velocity of the shells is 200 m/s, then find the speed of the car after second shot.

Explanation

To solve the problem, we will use the principle of conservation of momentum. Here are the steps:

### Step 1: Define the initial conditions
Initially, the railroad car (mass = 50m) is stationary, so the initial momentum is zero.

### Step 2: Analyze the first shell ejection
When the first shell (mass = m) is fired, the momentum before firing is equal to the momentum after firing.

...