The hero of a stunt film fires 50 g bullets from a machine gun, each at a speed of 1.0 km/s. If he fires 20 bullets in 4 seconds. What average force does he exert against the machine gun during this period?

Explanation

The momentum of each bullet
= (0.050 kg) (1000 m/s)
=50 kg-m/s.
The gun has been imparted this much amount of momentum by each bullet fired. Thus, the rate of change of momentum of the gun.
`=((50kg-m//s)xx20)/(4s)`
=250 N
In order to hold the gun, the hero must exert a force of 250 N against the gun.