Two rain drops of same radius are falling through air each with a steady speed of $5 \mathrm{~cm} / \mathrm{s}$. If the drops coalesce, the new steady velocity of big drop will be

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Aicharya · Accepted Answer

Terminal speed $\mathrm{v} \propto \mathrm{r}^2$ $\begin{array}{ll} 	herefore & \frac{v_1}{v_2}=\frac{r^2}{R^2}=\frac{r^2}{\left(2^{1 / 3} right)^2} \ 	herefore & v_2=v_1 	imes \frac{\left(2^{1 / 3} right)^2}{r^2}=5 	imes 2^{2 / 3}=5 	imes 4^{1 / 3} \mathrm{~cm} \mathrm{~s}^{-1} \end{array}$ ~

Two rain drops of same radius are falling through air each with a steady speed of $5 \mathrm{~cm} /…

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