Question

a bullet of mass 5g is fired from a gun weighing 5kg. If the initial velocity of the bullet is 250 ms-1 calculate the velocity which the gun recoils

Answer 1

here's Ur ans..

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Answer 2

The velocity at which gun recoils is 0.4m/s

Momentum of the system before firing is =  0 kgm/s ( Since, both the gun and the bullet are at rest )

After firing -  

Initial velocity = u = 250 m/s

Mass of bullet = m1 = 5g = 0.05kg

Therefore, the momentum of the bullet

= 0.05 × 250

= 12.5 kgm/s

Mass of the gun = 5 kg

Let the recoil velocity be = u2

According to the law of conservation of momentum,

Momentum before firing = momentum after firing

0 = 12.5 + 5u2

u2 = -5/12.5 kgm/s

= -0.4 m/s

Thus, the recoil velocity is 0.4 m/s in backward direction.