Question

A machine gun has a mass of 20 kg. It fires 35 g bullets at the rate of a bullets per second with a speed
of 400m/s. The force must be applied to the gun to keep it n position is

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Answer 1

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$\large{\boxed{\mathcal{\green{Note}}}}$

• The problem can be solved by using the concept of conservation of linear momentum
• The amount of force to be applied on the gun is equal to the momentum change per time

Here , given

• Mass of bullet = 35g = 0.035kg
• Velocity = 400 m/s
• Momentum of bullet = mv = 0.035 × 400 = 14Ns

The moment recoiled by gun is

• 14Ns = 20 × v
• Recoil velocity of gun = 14/20
• Recoil velocity of gun = 0.7 m/s

Hence Acceleration of gun = change in velocity /time

• Acceleration = $\dfrac{v-u}{t}$

• Acceleration = $\dfrac{0.7-0}{1}$

• Acceleration = 0.7m/s^2

Force = mass of gun × acceleration of gun

• Force = 20 × 0.7
• Force = 14N

$\large{\boxed{\mathfrak{\pink{Therefore\;Force\; required\;to\;keep\;in\;position\;is\;14N}}}}$

Answer 2

Answer:

Refer to the given attachment to get better understanding. Hope it will help you.