Question

a bullet of 100g is fired from a rifle of 20kg with the speed of 540km/hr. Determine the recoil velocity of the gun and it's direction​

Answer 1

Answer:

Mass of bullet, m=100g= 100/1000 kg=1/10 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= 1/10 ×100+20V=10+20V

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

i.e., 10+20V=0

20V=−10

or V=− 10/20 =−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.