Physics Class 11 Chapter 10. Mechanical Properties of Fluids | Page 8

where, r = radius of the body, V = terminal velocity and η = coefficient of viscosity.
This is called Stoke’ s law.
where, ρ = density of body, σ = density of liquid, η = coefficient of viscosity of liquid and, g = acceleration due to gravity 1. If ρ > ρ0, the body falls downwards. 2. If ρ < ρ0, the body moves upwards with the constant velocity. 3. If po << ρ, v =( 2r 2 ρg / 9η) Importance of Stoke’ s Law
1. This law is used in the determination of electronic charge by Millikan in his oil drop experiment.
2. This law helps a man coming down with the help of parachute.
3. This law account for the formation of clouds.
Flow of Liquid
1. Streamline Flow The flow of liquid in which each of its particle follows the same path as followed by the proceeding particles, is called streamline flow.
2. Laminar Flow The steady flow of liquid over a horizontal surface in the form of layers of different velocities, is called laminar flow.