A man fires a bullet of mass 150 g at a speed of 5 $\mathrm{m} / \mathrm{s}$. The gun is of one kg m

Question

A man fires a bullet of mass 150 g at a speed of 5 $\mathrm{m} / \mathrm{s}$. The gun is of one kg mass. By what velocity the gun rebounds backward?\

Professor PC Thomas Classes · Answer

(a): Mass of bullet $\left(m_{1}ight)=150 \mathrm{~g}=0.15 \mathrm{~kg}$;\ speed of bullet $\left(v_{1}ight)=5 \mathrm{~m} / \mathrm{s}$ and mass of gun\ $\left(m_{2}ight)=1 \mathrm{~kg}$. Before firing, total momentum is zero.\ After firing total momentum is $m_{1} v_{1}+m_{2} v_{2}$.\ From the law of conservation of momentum $m_{1} v_{1}+m_{2} v_{2}=0$\ or $v_{2}=\frac{-m_{1} v_{1}}{m_{2}}=\frac{-0.15 	imes 5}{1}=-.75 \mathrm{~m} / \mathrm{s}$