Density Determination of immiscible liquids by the Stevin's principle

Abstract

This work presents a didactic sequence followed by a low cost, easy to set up and easy to operate, experimental apparatus applied to the study of hydrostatics and, particularly, of a composition of immiscible liquids like water and oil. The Stevin Principle is used to analyze density of such liquids, having density of water (ρ =1000 kg/m 3 ) as reference. The teacher has a fundamental role in this proposal, since he is the mediator of the whole process, allowing the construction of connections between the existing concepts in student's cognitive structure with the new themes. The physical concepts were built through an expositive class, discussing on the physical concepts, history and everyday applications, as a form to better organize the previous knowledge of the students. Finally, an integrative reconciliation was made during the experimentation, intended to better provide meaningful learning. With the results, besides the observation that, in any given recipient, lower density liquids positionate itself above higher density ones, the students also determine the densities of such liquids, obtaining values similar to those found in literature. For example, the density of soy oil was determined as 0,87 g/cm 3 using the proposed experiment, against an accepted value of 0,891 g/cm 3 , a difference of about 2%.