Question

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

• A. one
• B. four
• C. two
• D. three

Answer 1

Answer: (D)

three

Answer 2

Change in momentum for each bullet fired is $= \frac{40}{1000}\times1200 = 48\,N$ If a bullet fired exerts a force of $48\, N$ on man?s hand so $?$ man can exert maximum force of $144\, N$, number of bullets that can be fired $= 144/48 = 3$ bullets.