A machine gun fires a bullet of mass 40 g with a velocity 1200 m/s 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? Solution) According to newtons 2nd law..... F=m(v-u)/t144=0.04*n*1200/1 (per second...so t=1s)n=3 bullets / sec
He force exerted by machine gun on man''''s hand in firing a bullet = change in momentum per second on a bullet or rate of change of momentum =(40/1000*)1200= 48 N .The force exerted by man on machine gun = 144 NTherefore, number of bullets fired = 3