F = 6πηrν, where F is the force exerted on a sphere of radius r which is moving through a fluid of viscosity η with a relative velocity ν; this equation holds at low velocities which are free from turbulence (called the Stokes region), turbulentsi puudumisel kehtiv seadus F = 6πηrν, kus F on jõud, mis on rakendatud läbi vedeliku viskoossusega η suhtelise kiirusega ν liikuvale sfäärile raadiusega r