Sat February 09, 2013 By: Arathi M

Derive Stoke's law dimensionally.

Expert Reply
Sat February 09, 2013

Suppose a spherical body of radius r moves at a speed v through a fluid of viscosity ?. The viscous force Facting on the body is given by,

F = 6 ? ? r v


Actual derivation of Stokes’s viscous drag theorem from definition of viscosity is beyond the scope of XII physics however following is a proof based upon dimensional analysis.

Given k = 6?

Viscous force on a small spherical ball of radius r moving with a velocity v in an infinite sea of liquid of viscosity ? is found to be dependent on r, v and ?.

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