A machine gun of mass 10 kg fires 20 g bullets with speed of 500 m/s at the rate of 10 bullets per second. To hold the gun steady in its position how much force is necessary?

Options

A. 200 N
B. 500 N
C. 100 N
D. 250 N

Answer

C

Explanation

Here, mass of the gun, M = 10 kg
Mass of the bullet, `m = 20 g = 20 xx 10^(-3)` kg
Speed of the bullet, v = 500 m/s
Number of bullets fired per second, n = 10
The force required to hold the gun is F = Rate of change of momentum of the bullets = Change in momentum of one bullet x Number of bullets fired per second = `mvn = 20 xx 10^(-3) xx 500 xx 10 N = 100 N`