Q. 34.1( 169 Votes )

# From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m s^{-1}. Calculate the initial recoil velocity of the rifle.

Answer :

Firstly, we will calculate the momentum of both rifle and bullet separately.

Momentum of bullet = Mass of bullet × Velocity of bullet

As we know that p= m × v

Putting the values in above equation we get:-

= 0.05 kg × 35 m/s (As 1 kg=1000 gram)

= **1.75 kg m/s** (i)

Similarly we solve for momentum of rifle

Momentum of rifle = Mass of rifle × Velocity

Putting the value in above equation we get:-

*=*4 kg × v m/s

=

**4v kg m/s**

We know that,

According to the law of conservation of momentum:

Momentum of bullet = Momentum of rifle1.75 = 4*v* [From (i) and (ii)]

v =

**v = 0.4375 m/s**

Therefore, the recoil velocity of the rifle is **0.4375 m/s**

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