Question

A machine gun of mass 12kg fires 25g bullets at the rate of 4 bullets per second with a velocity of 50 m/s. What force must be applied to the gun to hold it in position?
(1) 20N
(2) 12.5N
(3) 50N
(4) 75N​

Answer 1

Answer:

The answer is 62.5 N

Explanation:

In the given problem,  

m g =12 kg ; v B = 50 m/s  

Mass of the bullet = 25 g = 25×10 -3 kg  

No. of bullets fired/sec = 4

F = Change in momentum / time

  = mbvb - mbub / t

For t = 1 sec

Total mass of bullets in 1 second

mB = (50×25)/1000 = 1.25 kg

F = 1.25 x 50-0 /1 = 62.5 N

Answer 2

(c)The force must be applied to the gun to hold it in position is 50 N.

Explanation:

In question, the velocity of the bullets is 500 m/s not 50 m/s.

Further explanation:

Given the mass of the gun, M = 12 kg.

Mass of the bullet, m = 25 g.

Velocity of the bullet, v = 500 m/s.

Rate of firing bullets  = 4/sec

The change momentum for the bullet in one second,

$\Delta P=mv$

substitute the given values, we get

$\Delta P=25g\times500 m/s$

      = 12500 g.m/s =12.5 kg m/s

As per question, the gun fires 4 bullets per second.

The  total change in momentum in one second,

 $\Delta P_{total} =4\times12.50kgm/s$

              = 50 kg m/s

From the newton's second law the force applied to hold the gun is equal to  change in the momentum of the bullet,

Hence, the force must be applied to the gun to hold it in position is 50 N.

#Learn More: momentum

https://brainly.in/question/3576416