Question

From A rifle of mass 40 kg a bullet of mass 50 g is fired horizontally with initial velocity of 40 m/s . Calculate the initial recoil velocity of the rifle

Answer 1

Mass of Gun = 40 kg

Mass of Bullet = 50 g = 50/1000 Kg = 0.05 Kg

Velocity of Bullet = 40 m/s

Now,

Recoil Velocity = MV = mv

=> MV = - mv

=> 40 x V = - ( 0.05 x 40)

=> 40 V = -2 Kg m/s

=> V = -2/40 m/s

=> V = -0.05 m/s

Answer 2

hence the initial and final momentum remain constant therefore
(M+m)v=Mv' +mv''
(M+m)0=40×v' +0.05×40
-40v'=0.05×40
v'=-0.05m/s