They have different accelerations because of their masses. According to Newton's Second Law, an objects acceleration is inversely proportional to its mass. Therefore the object with the larger mass, in this case the gun, will have a smaller acceleration. In the same way, the less massive object, being the bullet, will have a higher acceleration.
Hope this helps :)
Sorry bro I just need points for my calculus exam
Answer:

Explanation:
Given:
- Length of the beam,

- speed of the beam,

- magnitude of the vertical magnetic field,

According to the Faraday's law the emf induced in a rod passing transversely through a magnetic field is given as:


