A machine gun fires 300 bullets per minute each with a velocity of 500 ms^-1. If the mass of each bullet is 4 g, the power of the machine gun is

Number of bullets, n=300

mass of bullet, m=4 g= 0.004 kg.

kinetic energy produced per second will be the power of the machine gun.

$\begin{array}{r}\text{ K. }\mathrm{E}=\mathrm{n}\times \frac{1}{2}{\mathrm{mv}}^2=300\times \frac{1}{2}\times 0.004\times {500}^2=150000\mathrm{J}\\ \text{ Power }=\frac{\text{ kinetic energy }}{\text{ time }}=\frac{150000}{60}=2500\text{ watt }\end{array}$