In this article we focus on the relation between magnitudes used to measure liquid viscosity coeficients with Stokes’ method. The related experiment is a low-cost, and apparently also a very simple one. Its simplicity however rests on the exacting conditions that must be fulfilled by the system. Otherwise, it is incorrect to assume the validity of the usual relation between magnitudes. We deal with some punctual aspects related to this laboratory practice. Their treatment may increase students’ interest and favor a better learning. We propose clarifying, complementary theoretical developments, most of them of qualitative type, which may be incorporated to the experiment in opportune moments, so as to help students’ deeper comprehension of the subject. We also present an improved experimental design with several measured results, their analysis and the conclusions. We finally expose a brief synthesis of the aspects under consideration, as well as some reflections about teaching practice.
viscosity measurement; Stokes; validity conditions; Reynolds
