Question

Diwali rocket is ejecting $50g$ of gases per second at a velocity of $400m{s}^{-1}$. The accelerating force on the rocket will be

• A. $22dyne$
• B. $20N$
• C. $20dyne$
• D. $100N$

Answer 1

The correct option is B

$20N$

Given data.

Mass of gas ejecting per second, $\frac{∆m}{∆t}=50g=0.05kg$

Velocity, $u=400\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$

Find the accelerating force on the rocket.

Formula used:

Upward thrust$=\frac{∆m}{∆t}\times u$

Now,

Upward thrust$=0.05\times 400$

Upward thrust$=20N$

Therefore the accelerating force on the rocket is $20N$

Hence, option B is correct.