Question

A machine gun fires a bullet of mass 40 gram with a velocity 1200 metre per second the man holding it can exert a maximum force of 14 newton on the gun how many bullets can keep fire per second at most

Answer 1

Answer:

We have given :

Mass and velocity of bullet are 40 g and 1200 m / sec respectively.

From second law of motion we know change in momemtum is directly proportional to net force.

$\displaystyle{\text{F} \ \propto \text{ma}}\\\\\\\displaystyle{\text{F}=\frac{\text{k m (v-u)}}{\text{t}} }\\\\\\\displaystyle{\text{F}=\frac{\text{k m (v)}}{\text{t}} }$

If we let ' k 'number of bullet fire per second.

Then we have :

m = 0.04

kgv = 1200 m /sec

F = 14 N

t = 1

sec k = ?

$\displaystyle{\text{14}=\frac{\text{k}\times0.04\times1200}{1} }\\\\\\\displaystyle{\text{k}=\frac{14}{48}}$

In question there might some error , else no. of bullet would never less than 1.If F = 144 N

Then ,

$\displaystyle{\text{k}=\frac{144}{48}}\\\\\\\displaystyle{\text{k}=3 }$

Hence the number of bullets can keep fire per second at most is 3 .