NEET2018PhysicsMechanical Properties of FluidsActual
A rain drop of radius 0.3 mm has a terminal velocity in air 1 ~ms ⁻¹ . The viscosity of air is 18 10⁻⁵ poise. Find the viscous force on the rain drops.
Options
- A2.05 10⁻⁷ ~N
- B1.018 10⁻⁷ ~N
- C1.05 10⁻⁷ ~N
- D2.058 10⁻⁷ ~N
Correct answer
B. 1.018 10⁻⁷ ~N
Step-by-step solution
Here, r =0.3 ~mm =0.3 10⁻³ ~m , v =1 ~ms ⁻¹ =18 10⁻⁵ poise =18 10⁻⁶ decapoise Viscous force, F =6 rv aligned & =6 22 7 (18 10⁻⁶ ) (0.3 10⁻³ ) 1 & =1.018 10⁻⁷ ~N aligned