A bullet of 10 g leaves the barrel of gun with a velocity of 600 m / s. If the barrel of gun is 50 cm long and mass of gun is 3 kg, then value of impulse supplied to the gun will be :

Solution

Physics sir · 3 steps

The gun gets exactly the impulse the bullet gets, just in the opposite direction.

1. Impulse on bullet. Impulse equals change in momentum. The bullet starts at rest, so its impulse is mv = 0.01 × 600 = 6 N s.
2. Third law. While the bullet moves through the barrel, the gas pushes the bullet forward and the gun backward with equal force for the same time. So the gun receives an equal and opposite impulse.

   J_(gun) = J_(bullet) = 0.01 × 600 = 6 N s

3. So. The impulse supplied to the gun is 6 N s, option (c). The barrel length and the gun's mass are not needed for this.

The idea to keep. Impulse is change in momentum, and action-reaction pairs share it equally. Extra data like barrel length is there to tempt you into finding force or time when you do not need them.

Answer from the NTA final answer key. Solution by PrepWiser.