Question

The machine gun fires $240$ bullets per minute. If the mass of each bullet is $10g$ and the velocity of the bullets is $600m{s}^{-1}$ ,the power (in $kW$ )of the gun is

• A. $43200$
• B. $432$
• C. $72$
• D. $7.2$

Answer 1

Answer: (D)

Work done by the gun
=Total kinetic energy of the bullets
$=n=\frac{1}{2}m{v}^2$
$=240\times \frac{1}{2}\times 10\times {\left(10\right)}^{-3}{\left(600\right)}^2$
$=120\times \frac{1}{2}\times 10\times 10^{-3}\times 600\times 600$
$\therefore Powerofgun=\frac{workdone}{timetaken}$
$=\frac{120\times 10\times 10^{-3}\times 600\times 600}{1min}$
$=\frac{120\times 10\times 360}{60}=120\times 10\times 6W$
$\frac{120\times 10\times 6}{1000}kW=7.2kW$