Question

Raindrops of different radii are falling through air. The terminal velocity of a drop of radius r will be proportional to 

(a) r³ 

(b) r² 

(c) r 

(d) 1/r

Answer 1

Correct Answer is: (b) r²

Terminal velocity is reached under the condition

6πηrv = 4/3 πr³ (ρ - σ)g

where the symbols have their usual meanings. Thus, v ∝ r².