Question

A 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)

$7.2$

Power $=\frac{W}{t}=\frac{N{(\Delta K.E)}_{bullet}}{t}$

$=\frac{240\times \frac{1}{2}\times m{v}^2}{60}$

$=2\times {10}^{-2}\times {\left(600\right)}^2$

$=7.2\times {10}^{3}W$

$=7.2kW$