Question

Find the velocity of a bullet of mass 10g which is fired from a pistol of
mass 1.5kg. The recoil velocity of the pistol is 2.5 m/s.

Answer 1

Answer:

Conservation of linear momentum gives,

m1v1+m2v2=0

m1v1=−m2v2

v1=m1−m2v2

Given, m1=10g=(100010)kg, 

m2=1 kg,

v2=−5m/s

∴v1=10/1000+1×5

or v1=500m/s.

Answer 2

Momentum of the gun = momentum of the bullet (law of conservation of momentum)

M = 1.5 kg

m = 10 g = 0.01 kg

v = ?

V = 2.5 m/s = recoil velocity

(M) x V = m x v

(1.5) x 2.5 = 0.01 x v

v = 375 m/s

:-)