From abstraction to measurement: a low-cost experimental study of friction torque using a physical pendulum and a smartphone

Abstract

Abstract This article proposes a low-cost experiment to overcome the didactic obstacles associated with the abstract concept of solid friction torque for students. By simply using a smartphone equipped with a free application (Fizziq) to analyse the oscillations of a physical pendulum, this study allows for the indirect measurement of a constant solid friction torque τ s at a fixed rotation axis, by exploiting the relationship between this torque and the observed linear decay of the oscillation amplitudes. The results show that the solid friction torque τ s remains constant regardless of the pendulum’s geometry, thus confirming the validity of the theoretical model. Finally, the introduction of measurement uncertainty analysis gives this approach a scientific rigour and didactic significance that are essential for students.