Question

3. 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

Given:-

→Mass of the rifle(M) = 4kg

→Mass of the bullet(m) = 50g

→Velocity of the bullet(v) = 35m/s

To find:-

→Initial recoil velocity of the rifle(V)

(It means recoil velocity of the rifle)

Solution:-

Firstly,let's convert the mass of the bullet from g to kg.

=>1g = 0.001kg

=>50g = 50(0.001)

=>0.05kg

By using Law of Conservation of momentum, we get:-

=>M(-V)+mv = 0

=>V = mv/M

=>V = 0.05×35/4

=>V = 1.75/4

=>V = 0.4375m/s

Thus,initial recoil velocity of the rifle is

0.4375m/s.

Some Extra Information:-

Conservation of momentum: When external force acting on a body is zero,then the total momentum of the body remains constant/conserved. This is called 'Law of Conservation of Momentum'.