JEE Mains Previous Years Questions with Solutions

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1

AIEEE 2004

A machine gun fires a bullet of mass $40$ $g$ with a velocity $1200m{s^{ - 1}}.$ The man holding it can exert a maximum force of $144$ $N$ on the gun. How many bullets can he fire per second at the most?
A
Two
B
Four
C
One
D
Three

Explanation

Assume the man can fire $n$ bullets in one second.

$\therefore$ change in momentum per second $= n \times mv = F$

[ $m=$ mass of bullet, $v=$ velocity, $F$ = force) ]

$\therefore$ $n = {F \over {mv}} = {{144 \times 1000} \over {40 \times 1200}} = 3$