Question

A cannon is mounted on a railroad car. The cannon shoots a 1.75 kg ball with a muzzle velocity if 300 m/s. The cannon and the railroad car together have a mass of 4500 kg. if the ball, cannon, and railroad car are initially at rest, what is the recoil velocity of the car and cannon?

Answer 1

which way is the cannon pointed? Especially the shooting angle.

If horizontal, along the direction of the tracks...

momentumcannon+momentumcar=zero
1.75*-300=4500V