Question

Diwali rocket is ejecting $50\, g$ of gasses at a velocity of $400 \,m/s$ . The accelerating force on the rocket will be

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

Answer 1

Answer: (B)

20 N

Answer 2

The accelerating force on the rocket
upward thrust $=\frac{\Delta m}{\Delta t} \cdot u$
Given, $\frac{\Delta m}{\Delta t}=50 \times 10^{-3} kg / s ,\, v=400\, m / s$
So, accelerating force $=50 \times 10^{-3} \times 400$
$=20\, N$