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

Question

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

Tardigrade Admin · Accepted Answer

u = velocity of bullet (dm/dt) = Mass thrown per second by the machine gun = Mass of bullet × Number of bullet fired per second =10 g× 10 bullet/sec = 100 g/sec=0.1 kg/sec ∴ Thrust =(u dm/dt)=500 × 0.1 =50 N

Q. A machine gun is mounted on a $2000 k g$ car on a horizontal frictionless surface. At some instant the gun fires bullets of mass $10 g m$ 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

$550 N$

$50 N$

$250 N$

$250$ dyne

u = velocity of bullet

$\frac{d m}{d t}$ = Mass thrown per second by the machine gun

= Mass of bullet $\times$ Number of bullet fired per second

$= 10 g \times 10$ bullet/sec $= 100 g / sec = 0.1 k g / sec$

$∴$ Thrust $= \frac{u d m}{d t} = 500 \times 0.1$

$= 50 N$

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

550N

50N

250N

250 dyne