Q. A machine gun fires $n$ bullets per second, each of mass $m.$ If the speed of each bullet is $u$, then the force of recoil is
A) $mng$
B) $mnv$
C) $mnvg$
D) $\frac{mnv}{g}$
Explanation
(b) Change of momentum of one bullet is $mv$
Time for 1 bullet $= \frac{1}{n}$
$\therefore$ Force = time rate of change of momentum
$= \frac{mv}{1/n} = mnv$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.