Question

While firing a bullet, the gun must be held tight to the shoulder.

1. Which conservation law helps you to explain this

2. “In the firing process, the speed of the gun is very low compared to the speed of the bullet.” Substantiate the above statement using mathematical expressions.

3. A shell of 20kg moving at 50m/s bursts in to two parts of masses 15kg and 5kg. If the larger part continues to move in the same direction at 70 m/s. What is the velocity and direction of motion of the other piece.

Answer 1

1. Conservation of momentum.

2. Total momentum is conserved

∴ mu + MV = 0

V = \(\frac{−mu}{M}\) M is very large. Hence v is small

3. MV = m₁ u₁ + m₂ u₂

20 × 50 = 5u₁ + 15 × 70

5u₁ = ^–50

u₁ = ^–10m/s.