Question

A machine gun fires a bullet of mass 40 g with a
velocity 1200 m/s. The man holding it can exert a
maximum force of 144 N on the gun. The number
of bullets he can fire per second will be

Answer 1

F=mna

144=0.04×1200/1×n

n=144/48

=4

Answer 2

Answer:

The number of bullets man can fire will be 3.

Explanation:

Given;-

        Mass of bullet, m = 40 g

     Velocity of bullet, v = 1200 m/s

         Force on man, F = 144 N

Let the number of bullets man can fire per second be 'n'.

Now, we know that;-

  Force on Man = - Force on bullet

                    F  = dP/ dt [where P = momentum] ... by formula.

                     F = mv - 0/ t  [since, initial momentum = 0]

                     F = ( mv/t ) × n [where, n = number of bullets]

                 144 = 40 × 1200 × n / 1000 × 1

                 144 = 48 × n

                     n = 144/48

                    n = 3

Hence, the man can fire 3 bullets per second.

Hope it helps! ;-))