A bullet of mass 20g is horizontally fired with a horizontal velocity 150m/s from a pistol of mass 2kg. What is the recoil velocity of the pistol?
By taking mass of pistol 0.020g.
Using the law of conservation of linear momentum.
m1= mass of gun.
m2= mass of bullet.
u1,v1= initial and final velocities of gun.
u2,v2= initial and final velocities of bullet.
m1u1+m2u2=m1v1+m2v2
u1=0; u2=0
So,
0=m1v1+m2v2
Recoil velocity v1=
-(m2×v2)/(m1)
Negative sign indicates that recoil velocity is always opposite to the firing velocity/bullet velocity.
M1=15kg.
M2=20g=20×10^-3 kg
[1kg=1000g]
u1=u2=0
V2=150m/s
recoil velocity ,V1=-(m2×V2)/m1 = -0.2m/s