Question

15. A light bullet is fired from a heavy
gun.
a) Choose the CORRECT.
i) Speed of the gun and the
bullet are equal.
ii) Momenta of the bullet and
gun are equal in magnitude
and opposite in direction.
iil) Momenta of the gun and
bullet are equal in
magnitude and are in the
same direction
iv) Velocity of gun and bullet
are equal.
b) By using a suitable
conservation law in Physics,
prove your above answer. (2)​

Answer 1

Answer:

1 part as the law of conservation of momentum the gun will recoil

Answer 2

Answer:

ii) Momenta of the bullet and gun are equal in magnitude but opposite in direction.

b) Conservation of Momentum.

Explanation:

By conservation of Momentum

Before the gun is fired

The momenta of the gun and the bullet is equal to 0

$P_g+V_g =0\\M_gV_g + M_bV_b = 0$

After the gun is fired too the momentum of the gun and bullet should be 0.

$M_gV_g + M_bV_b = 0$

As the bullet is lighter and the gun is heavy. The velocity of the bullet is much greater than the reconciliation velocity of the gun.

So, After the gun is fired the momentum of the gun and bullet should be 0

$M_gV_g + M_bV_b = 0$

As the bullet is lighter and the gun is heavy. The velocity of the bullet is much greater than the reconciliation velocity of the gun.

So,

$M_gV_g = - M_bV_b\\P_g = - P_b$

$M_gV_g = - M_bV_b\\P_g = - P_b$

Hence proved

Momenta of the bullet and gun are equal in magnitude but opposite in direction.