Question

From a rifle of mass 4 kg, a bullet
of mass 50 g is fired with an
Initial velocity of 35 ms
Calculate the initial recoil velocity
of the rifle.​

Answer 1

(M1)Mass of rifle = 4 kg

(M2)Mass of bullet = 50 g = 0.05 kg

(V1)Velocity of bullet = 35 m/s

(V2)Recoil velocity of rifle = ?

According to the law of conservation of momentum

Momentum of rifle = momentum of bullet

m1v1 = m2v2

4kg * v1 = 0.05 * 35 m/s Therefore v1 = (0.05 * 35 ) / 4 = 1.75/4

v1 = 0.4375 m/s

Therefore , recoil velocity of rifle = 0.4375 m/s

Answer 2

$\underline{ \underline{ \bf{Answer}}} : - \\ \implies \: \bf{recoil \: velocity \: = 0.44 \: \frac{m}{s} } \\ \\ \underline{\underline{\bf {Step - by - step \: explanation}}} : - \\ \\ \underline{\bf{ To \: find}} - \\ \\ \bf{find \: recoil \: velocity \: of \: rifle} \\ \\ \underline{\bf{Solution}} : - \\ \\ \bf{velocity \: of \: \: bullet \:( v1) = 35 \: \frac{m}{s} } \\ \\ \bf{ mass \: of \: bullet \: (m1) = 50 \: g = 0.050 \: kg} \\ \\ \bf{mass \: of \: rifle \: (m2) = 4 \: kg } \\ \\ \bf{recoil \: velocity \: of \: rifle \: (v2) =? }$

Since,No external force acts on the rifle then the change in momentum is zero.

Momentum of rifle = (momentum of bullet)

$\implies \: \bf{m2 \: v2 = m1 \: v1} \\ \\ \implies \: \bf{4 \times v2 = 0.050 \times 35} \\ \\ \implies \: \bf{v2 = 0.44 \: \frac{m}{s} } \\ \\ \bf{recoil \: velocity \: of \: rifle \: is \: 0.44 \: \frac{m}{s} }$