Question

25. A machine gun is mounted on a 2000 kg car on a horizontal frictionless surface. At
some instant the gun fires bullets of mass 10 gm with a velocity of 500 m/sec with
respect to the car. The number of bullets fired per second is ten. The average thrust
on the system is
(a) 550 N
(b) 50 N
(c) 250 N
(d) 250 dyne​

Answer 1

Answer:-

-

The average thrust exerted by ejected bullet is nothing but

the momentum gained by that bullet when fired

- Momentum can be understood as a force or an energy

gained by a moving object

- This force is given by F mv (mass and velocity of

bullet)

- But the number of bullets per second also amplifies this

momentum, therefore, the force in this case is expressed

as F n x mv ('n' is the number of bullets)

- Converting the mass of a bullet in kilograms we get

m=0.010 kgs.

- Check if all the units involved either belong to the SI

(prefered) or CGS system.

- Substituting the values of mv and n in the above formula

for 'F' we get,

F 10 x 0.010 x 500 = 50 N