Question

A bullet of mass 20g is horizontal fired with a velocity 150ms^-1 from a pistol of mass 20g. What is recoil velocity of the pistol?

Answer 1

Here Linear momentum is conserved.

According to law of conservation of momentum.

Consider the mass of bullet as m1 = 20 g =20/1000=0.02 kg

The mass of pistol m2 = 2 kg as it is impossible for me pistol to be equal to bullet

Here u = 150 m/s

v =?

m2v = m1 u

2 v = 0.02(150)

v = 0.02(150) /2

v =2(150)/200

v = 1.5 m/s

Hence the recoil velocity of pistol is 1.5 m/s.

Answer 2

Formula to find recoil velocity (v) of pistol is

v = m1v1 / m2
= (20 * 10^-3 * 150) / (2)
= 1.5 m/s

Recoil velocity of pistol is 1.5 m/s

[Note: It is given that both mass of bullet and mass of pistol is same i.e 20g. It’s impossible. Hence i took mass of pistol as 2 kg]