Laws Of Motion Question 50

Question: At a certain instant of time the mass of a rocket going up vertically is 100 kg. If it is ejecting 5 kg of gas per second at a speed of 400 m/s, the acceleration of the rocket would be (taking $ g=10m/s^{2}) $ [NCERT 1984]

Options:

A) $ 20m/s^{2} $

B) $ 10m/s^{2} $

C) $ 2m/s^{2} $

D) $ 1m/s^{2} $

Show Answer

Answer:

Correct Answer: B

Solution:

The acceleration of a rocket is given by $ a=\frac{v}{m}( \frac{\Delta m}{\Delta t} )-g=\frac{400}{100}( \frac{5}{1} )-10 $

$ =(20-10)=10m/s^{2} $



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