Question

A machine gun is mounted on a 2000kg car on a horizontal frictionless surface. At some instant, the gun fires bullet of mass 10gm with a velocity of 500m/s with respect to the car. The number of bullets fired per second is 10. The average thrust on the system is...

Answer 1

                         u = velocity of bullet             \[\frac{dm}{dt}=\]Mass thrown per second by the machine gun                = Mass of bullet × Number of bullet fired per second                \[=10\ g\times 10\ bullet/\sec \]\[=100\ g/\sec \ =\ 0.1\ kg/\sec \]             \[\therefore \] Thrust \[=\frac{udm}{dt}=500\times 0.1=50\ N\]