Application of classical concepts of physics in engineering practice.Stokes' Law as conceptual tool in analysis of Petroleum Dehydration Processes Several physical processes have been used in breaking of water-in-crude oil emulsions (petroleum dehydration); heating, water and diluents addition and electrical field application are the most common ones. In all cases, the effect of each operational parameter on the main variables that determine sedimentation rate of water droplets in emulsions can be predicted by Stokes' Law, which constitutes a simple mathematical expression very useful for chemical engineers in design and operation of separation processes of emulsified systems.