Question.
From a rifle of mass 4 kg, a bullet of mass 50 g is fired with a speed of 35 ms–1 Calculate the recoil speed of the rifle
From a rifle of mass 4 kg, a bullet of mass 50 g is fired with a speed of 35 ms–1 Calculate the recoil speed of the rifle
Solution:
Mass of rifle $=4 \mathrm{~kg}$
Let velocity of recoil of rifle $=\mathrm{v}$
Momentum of the rifle $=4 \times \mathrm{v}$
Mass of bullet $=50 \mathrm{~g}=\frac{50}{1000} \mathrm{~kg}=0.05 \mathrm{~kg}$
Velocity of bullet $=35 \mathrm{~ms}^{-1}$
Momentum of bullet $=0.05 \times 35$
Using the law of conservation of momentum,
momentum of the rifle $+$ momentum of the bullet
$=4 \times \mathrm{v}-0.05 \times 35=0$
or $\quad v=\frac{0.05 \times 35}{4}=0.4375 \mathrm{~ms}^{-1}$
Mass of rifle $=4 \mathrm{~kg}$
Let velocity of recoil of rifle $=\mathrm{v}$
Momentum of the rifle $=4 \times \mathrm{v}$
Mass of bullet $=50 \mathrm{~g}=\frac{50}{1000} \mathrm{~kg}=0.05 \mathrm{~kg}$
Velocity of bullet $=35 \mathrm{~ms}^{-1}$
Momentum of bullet $=0.05 \times 35$
Using the law of conservation of momentum,
momentum of the rifle $+$ momentum of the bullet
$=4 \times \mathrm{v}-0.05 \times 35=0$
or $\quad v=\frac{0.05 \times 35}{4}=0.4375 \mathrm{~ms}^{-1}$