Question

Bullet of mass 10g is fired with speed 1000 m/s from gun of mass 2kg. Recoil speed of gun will be​

Answer 1

Answer

Recoil velocity of the gun = - 5 m/s

Given

Mass of the bullet = 10 g = 0.01 kg

Velocity of the bullet = 1000 m/s

Mass of the gun = 2 kg

To Find

Recoil velocity of the gun = ? m/s

Key Points

This kind of question's can easily solved by the concept , Conservation of momentum

Solution

Mass of the gun , M = 2 kg

Mass of the bullet , m = 0.01 kg

Initial velocity of the gun , u = 0 m/s

Initial velocity of the bullet , u = 0 m/s

Final velocity of the bullet , V = 1000 m/s

Final velocity of the gun , v = ? m/s

This is the recoil velocity of the gun

Apply conservation of momentum ,

⇒ mu + Mu = mv + MV

⇒ (0.01)(0) + (2)(0) = (0.01)(1000) + (2)V

⇒ 0 + 0 = 10 + 2V

⇒ 2V = - 10

⇒ V = - 5 m/s

So , Recoil velocity of the gun = - 5 m/s

Note : Negative sign shows opposite direction of the gun