Question

A gun of mass M kg fires a shell of mass 1.5 kg with a velocity of 150 ms-1 and refills with a velocity of 1.5 m s-1 calculate the mass of the gun

Answer 1

Momentum is conserved. The shell and gun initially have a total momentum value of 0. Later on, the total is still 0.

The shell is given momentum in one direction, the gun is given the same amount of momentum, but in the opposite direction.

The total is 0.

The bullet momentum (mass x velocity) =(m x v)
= 1.5 kg x 150m/s
= 225 kg m/s

The gun must have the same amount 225 chunks of momentum, but in the opposite direction, so we call this - 225 kg m/s
For the gun,
momentum (mass x velocity) =(M x v) = -225 kg fom/s

Therefore mass of gun ,M=-225/-1.5=150 kg