Question

A bullet of mass 2 Kg is fired from a gun of mass 10 kg with a velocity of 100 m/s. Calculate the velocity of recoil.

Answer 1

Answer:

Mass of bullet, m=100g=  

1000

100

​  

kg=  

10

1

​  

kg

Velocity of bullet, v=100ms  

−1

 

Mass of gun, M=20kg

Let recoil velocity of gun =V

Before firing, the system (gun+bullet) is at rest, therefore, initial momentum of the system =0

Final momentum of the system = momentum of bullet + momentum of gun

=mv+MV=  

10

1

​  

×100+20V=10+20V

Applying law of conservation of momentum, Final momentum = Initial momentum

i.e., 10+20V=0

20V=−10

or V=−  

20

10

​  

=−0.5ms  

−1

.

Negative sign shows that the direction of recoil velocity of the gun is opposite to the direction of the velocity of the bullet.

Explanation: