Question

A machine gun fires 360 bullets per minute. Each bullet moves with a velocity of 600 ms${}^{-1}$. If the power of the gun is 5.4 kw, the mass of each bullet is,

• A. 5 kg
• B. 0.5 kg
• C. 0.05 kg
• D. 5 gm

Answer 1

The correct option is D 5 gm

Given,

Number of bullets, $n=360nos.$

Mass of bullet, $m$

Power, $=5400watt$

Kinetic energy of 360 bullets, $K.E=n\times \frac{1}{2}m{v}^2=360\times \frac{1}{2}\times m\times {600}^2=648\times {10}^{5}mJ$

$Power=\frac{kineticenergy}{time}$

$5400=\frac{648\times {10}^{5}m}{60}$

$m=5\times {10}^{-3}kg=5gram$

Hence, weight of each bullet is $5gram$