Question : The ratio of the terminal velocities of two drops of radii R and R/2 is
a) 2
b) 1
c) 1/2
d) 4
Doubt by Faisal
Solution :
We know,
Terminal velocity of a drop falling through a viscous medium is given by
v=2(⍴-𝜎)r²g/9η
v∝r²
v1/v2=r1²/r2²
v1/v2=(r1/r2)²
v1/v2=[R/(R/2)]²
v1/v2=[2/1]²
v1/v2=4/1
v1:v2=4:1
Hence, d) 4 would be the correct option.