Using a large amplitude pendulum in a learning cycle strategy

Abstract

Experiments with a damped simple pendulum were carried out and modelled for large amplitude motion with physics students in a mechanics laboratory course of the first year of the university. The equation of motion used for this pendulum was the equation of a damped pendulum where the simplification for small angles was avoided. In this investigation, the damping of this pendulum was assumed to be proportional and opposite to its velocity. This hypothesis was verified experimentally and the constant of damping was measured from the experimental data. This constant was introduced in the equation of motion of the pendulum to be solved by a numerical method. The comparison made between the numerical solution and experimental data was successful, giving students confidence in the strategy followed. With the support of the teacher students modelled empirically the period of the pendulum as a quadratic function of its amplitude and made good predictions of the behavior of the pendulum for other amplitudes by using the numerical solution. On completion of the course, in a revision of the students reports, it was possible to propose an empirical equation as an analytical solution for this pendulum, an important result of the learning cycle carried out in the study of the pendulum. In this process of teaching, students developed scientific skills that were evaluated and both students and teachers were able to build new knowledge about a pendulum with large amplitude.