Question

A machine gun fires a bullet of mass $40g$ with a velocity $1200m{s}^{-1}$. The man holding it can exert a maximum force of $144N$ on the gun. How many bullets can he fire per second at the most?

• A. $2$
• B. $4$
• C. $1$
• D. $3$

Answer 1

The correct option is D $3$

Given : Mass of one bullet $m=40$ $gm$ $=0.04$ $kg$

Velocity of bullet $v=1200$ $m{s}^{-1}$

Maximum exerted by man $F=144$ N

Let the total number of bullets fired per sec be $n$

Using $F=\int Pdt$ $⟹F=P\Delta t$

Thus this force balances the net linear momenta offered by the bullets in one sec.

$\therefore$ $F=nmv$

$144=n\left(0.04\right)\left(1200\right)$ $⟹n=3$ bullets per sec