Question

a rain drop of radius 0.2 mm falling with velocity of 2m/s. if coefficient of viscosity of air is 1.8×10^-104 Ns/m^2, determine viscous force acting on a drop

Answer 1

Critical velocity is the velocity of  liquid flow upto which its flow is streamlined [laminar]and after which it flow becomes turbulent.

Answer 2

Answer:

The viscous force acting on a drop is $135.65\times10^{-8}\ N$

Explanation:

Given that,

Radius of rain drop = 0.2 mm

Velocity $v=2\ m/s$

Coefficient of viscosity of air $\eta=1.8\times10^{-4}\ Ns/m^2$

We know that,

The viscous force acting on a drop is

$F = 6\pi r\eta v$

$F=6\times3.14\times2\times10^{-4}\times1.8\times10^{-4}\times2$

$F = 135.65\times10^{-8}\ N$

Hence, The viscous force acting on a drop is $135.65\times10^{-8}\ N$.