Q 11-09-073JEE MainJEE Main 2024 (8 Apr, Shift 2)Easy
Small water droplets of radius $0.01\ \text{mm}$ are formed in the upper atmosphere and are falling with a terminal velocity of $10\ \text{cm/s}$. Due to condensation, if 8 such droplets coalesce and form a larger drop, the new terminal velocity will be ______ cm/s.
Numerical value type. Enter your answer.
Answer: 40
Volume is conserved: $8r^3 = R^3 \Rightarrow R = 2r$.
Terminal velocity $v_t \propto r^2$, so $v_t' = 4\times10 = 40\ \text{cm/s}$.
Solution by Sreeraj P, M.Sc Physics