Q. A machine gun fires 120 shoots per minute. If the mass of each bullet is 10 g and the muzzle velocity is 800 $ms^{- 1}$, the average recoil force on the machine gun is
A) 120 N
B) 8 N
C) 16 N
D) 12 N
Explanation
(c) $F = v\frac{\mathrm{\Delta}m}{\mathrm{\Delta}t}$
Here, $\frac{\mathrm{\Delta}m}{\mathrm{\Delta}t} = \frac{nm}{t} = \frac{120 \times 10 \times 10^{- 3}}{60} = 20 \times 10^{- 3}$ kg $s^{- 1}$
$\therefore\ \ \ \ F = 800 \times 20 \times 10^{- 3}$N = 16 N
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.