WBJEE · Physics · Mechanical Properties of Fluids
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 coefficient of viscosity of air \(\approx 1.8 \times 10^{-5} \mathrm{N}-sm^{-2}\) ? (Neglect buoyancy of air)
- A \(49 \mathrm{ms}^{-1}\)
- B \(98 \mathrm{ms}^{-1}\)
- C \(392 \mathrm{ms}^{-1}\)
- D \(980 \mathrm{ms}^{-1}\)
Answer & Solution
Correct Answer
(B) \(98 \mathrm{ms}^{-1}\)
Step-by-step Solution
Detailed explanation
Terminal velocity, \(v=\frac{2}{9} r^{2} \frac{(\rho-\sigma)}{\eta}\) g Neglecting buoyancy effect of the fluid, \(v=\frac{2}{9} \cdot \frac{\rho}{\eta} r^{2} g\) Putting the given values, we get…
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