What will be the approximate terminal velocity of a rain drop of diameter \(1.8 \times 10^{-3} \mathrm{~m}\), when density of rain water \(\approx 10^{3}\) \(\mathrm{kgm}^{-3}\) and the co-efficient of viscosity if air \(\approx 1.8 \times 10^{-5} \mathrm{Nsm}^{-2}\) ? (Neglect buoyancy of air)

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What will be the approximate terminal velocity of a rain drop of diameter \(1.8 \times 10^{-3} \mathrm{~m}\), when density of rain water \(\approx 10^{3}\) \(\mathrm{kgm}^{-3}\) and the co-efficient of viscosity if air \(\approx 1.8 \times 10^{-5} \mathrm{Nsm}^{-2}\) ? (Neglect buoyancy of air)

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kritika · Answer 1 · 2021-12-15T12:23:34+0000

Ans: (B)
Hint \(: \sigma \frac{4}{3} \pi r^{3} g=6 \pi \eta r v, v=\frac{2}{9} \frac{\sigma r^{2} g}{\eta}, v=\frac{2}{9} \times \frac{10^{3} \times 0.9 \times 10^{-3} \times 0.9 \times 10^{-3} \times 9.8}{1.8 \times 10^{-5}}, v=98 \mathrm{~m} / \mathrm{s}\)

What will be the approximate terminal velocity of a rain drop of diameter \(1.8 \times 10^{-3} \mathrm{~m}\), when density of rain water \(\approx 10^{3}\) \(\mathrm{kgm}^{-3}\) and the co-efficient of viscosity if air \(\approx 1.8 \times 10^{-5} \mathrm{Nsm}^{-2}\) ? (Neglect buoyancy of air)

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