A machine gun is mounted on a 2000 ,kg car on a horizontal fricti… - Vidyadip

MCQ

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 ........ $N$

A
$550$
✓
$50$
C
$250$
D
$25$

✓

Answer

Correct option: B.

$50$

b
(b) $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$

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