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Physics · MECHANICAL PROPERTIES OF FLUIDS
हिन्दीEight identical spherical raindrops of water are falling vertically through air with a terminal velocity of \( 5\text{ cm/s} \). If all eight raindrops combine to form a single larger spherical drop, the terminal velocity of the combined drop (assuming the buoyancy of air remains negligible) will be:
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Correct answer · Option A
\( 20\text{ cm/s} \)
Explanation
Volume conservation: \( \frac{4}{3}\pi R^3 = 8 \times \frac{4}{3}\pi r^3 \implies R = 2r \). Terminal velocity \( v_{\text{t}} \propto r^2 \), so \( v_{\text{t}}' = v_{\text{t}} (\frac{R}{r})^2 = 5 \times 2^2 = 20\text{ cm/s} \).
