Q. A rocket of mass 1000 kg is exhaust gases at a rate of $4\ {kgs}^{- 1}$ with a velocity $3000\ {ms}^{- 1}.$ The thrust developed on the rocket is
A) 12000 N
B) 120 N
C) 800 N
D) 200 N
Explanation
(a) Mass of the rocket $m = 1000\ kg\ $
$\frac{\mathrm{\Delta}m}{\mathrm{\Delta}t} = 4\ {kgs}^{- 1},\ \ v = 3000\ {ms}^{- 1}$
Thrust on the rocket
$F = - v\frac{\mathrm{\Delta}m}{\mathrm{\Delta}t}$
$= - 3000 \times 4$
$= - 12000\ N$
(Negative sign indicates that thrust applied in a direction opposite to the direction of escaping gas)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.