Modelling free-fall motion and vortex flows through the use of Tracker software: an inquiry-based teaching learning sequence

This article presents a teaching–learning sequence based on the inquiry-based learning approach, designed to help high-school students gain a deeper understanding of the physical principles of the free fall of bodies and the role of viscous resistive forces. The activity, centred on the use of the open-source video analysis software Tracker, enables students to explore the motion of small-radius spheres of different masses and materials, and to experimentally infer the effect of air viscosity on the motion of a lightweight polystyrene ball by means of the Tracker’s built-in modelling tool. An extension of the activity is also proposed, focusing on the vortex-induced motion to provide a clearer explanation of the observed phenomena. The comparison of the motion laws of balls of different mass allows students to overcome common misconceptions related to dynamics and engage with fundamental aspects of fluid dynamics, which are often addressed only superficially in traditional instruction. The experiment is conceived not simply as a laboratory task, but as an educational experience aimed at developing scientific curiosity and critical autonomy through direct experimentation.