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Stokes Law Calculator

Stoke's law states that at low velocities the frictional force on a spherical body moving through a fluid at constant velocity is equal to 6 π times the product of the velocity, the fluid viscosity, and the radius of the sphere. In short, a sphere moving through a viscous fluid is directly proportional to the velocity of the sphere as well as the radius of the sphere, and the viscosity of the fluid.

Stokes Law Calculator

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Table of Contents:

    Formula

    Fall or Settling Velocity :
    Vt = gd2 (ρp - ρm)/18μ

    Acceleration of Gravity :
    g= 18 μ Vt /d2p - ρm)

    Particle Diameter :
    d= √18 μ Vt /g (ρp - ρm)

    Density of Medium :
    ρm = ρp - 18 μ Vt/ d2

    Particle Density :
    ρp = 18 μ Vt /d2+ ρm

    Viscosity of Medium :
    μ = gd2( ρp - ρm)/18 Vt

    Where,
    Vt = Fall or Settling Velocity,
    g = Acceleration of Gravity,
    d = Particle Diameter,
    ρm = Density of Medium,
    ρp = Particle Density,
    μ = Viscosity of Medium.

    Stoke's Law is defined as the basis of the falling - sphere viscometer. In the viscometer the fluid is stationary in a vertical glass tube. This online Stokes Law Calculator is useful in calculating various parameters of fluid in viscometer.

    Example:
    Calculate the fall or settling velocity (Vt) for the given details through Stoke's Law formula.
    Acceleration of Gravity (g) = 25 m/s2
    Particle Diameter (d) = 15 m
    Density of Medium (ρm) = 5 kg/m4
    Particle Density (ρp) = 10 kg/m3
    Viscosity of Medium (μ) = 20 kg/m-s

    Solution:
    Apply formula:
    Vt = gd2 (ρp - ρm)/18μ
    t= 25*15 (10-5)/18*20
    Fall or Settling Velocity (Vt) = 78.13 m/s