Question

A bullet of mass 0.01 kg is fired from a gun weighing 5.0 kg. If the initial speed of the bullet is 250 m/s, calculate the speed with which the gun recoils.

• A. -0.50 m/s
• B. - 0.25 m/s
• C. + 0.05 m/s
• D. +0.25 m/s

Answer 1

The correct option is A -0.50 m/s

Let the recoil velocity of gun be $V$.

Mass of gun $M_{gun}=5.0kg$

Mass of bullet $M_{bullet}=0.01kg$

Velocity of bullet $V_{bullet}=250m/s$

Initial momentum of the system $P_i=0$

Applying the conservation of linear momentum : $P_f=P_i$

Or $M_{gun}V+M_{bullet}{V}_{bullet}=0$

Or $5\times V+0.01\times 250=0$

$⟹V=-0.5m/s$