N bullets each of mass m are fired with a velocity v m/ s at the rate of n bullets per sec., upon a wall. If the bullets are completely stopped by the wall, the reaction offered by the wall to the bullets is?

1 Answer

nmv

Explanation:

The reaction (force) offered by the wall will be equal to the rate of change of momentum of bullets hitting the wall. Hence reaction is

=\frac{\text{final momentum}-\text{initial momentum}}{\text{time}}

=\frac{N(m(0)-m(v))}{t}

={N}/t (-mv)

=n(-mv)\quad(N/t=n=\text{number of bullets per second})

=-nmv

The reaction offered by the wall in opposite direction is

=nmv