Newtons laws of motion

Question

A cannon is fi red horizontally from a platform. The platform rests on a flat, icy, frictionless surface. Just after the shell is fired and while it is moving through the barrel of the gun, the shell (mass 3.2 kg) has an acceleration of 2500 m/s2. At the same time, the cannon has an acceleration of 0.76 m/s2. What is the mass of the cannon?

Answer 1

Newton 2 implies that the total momentum of the system will be 0, and it's rate of change will also be zero.

m₁a₁ + m₂a₂ =0 so 3.2 x 2500 + m₂ x (-0.76) = 0

Solve for mass of cannon, m₂ = 10526 kg