Question

# A machine gun has a mass of 20 kg. It fires 30 g. bullets at the rate of 400 bullets per second with a speed of ( 400 mathrm{ms}^{-1} ). What force must be applied to the gun to keep it in position?

Solution

( m g=20 mathrm{kg} )

( m_{b}=30 mathrm{g}=0.03 mathrm{kg} )

rate of bulets fired ( =400 / mathrm{s} )

( mathrm{V}_{b}=400 mathrm{m} / mathrm{s} )

ab (acceleration) ( =mathrm{V}_{b} times ) rate

[

begin{aligned} & 400 times 400=16000 mathrm{m} / mathrm{s}_{2} text { Force, } mathrm{F}=mathrm{m}_{b} times a_{b}=0.03 times 160000=4800mathrm{N} end{aligned}

]