A physical pendulum with variable point of suspension (and, as an outcome, variable inertia moment) is experimentally analysed. In particular, the period of the small oscillations as a function of position of the suspension point is measured using three different methods: a smartphone used both as an independent tool or as a data-logger and commercial photo-gate. The experimental results are successfully compared with theoretical calculations based on the addition of inertia moments and the Steiner theorem.

Martin Monteiro, Cecilia Stari, Cecilia Cabeza, Arturo C. Marti

We would like to thank Sebastian Staacks, developer of PhyPhox, who made a more accurate version of the “Pendulum” experiment especially for the purpose of this work. The experiment can be installed following this QR:

Experimental setup:

Measuring with PhyPhox:

Measuring with Vernier’s photogate:

Measuring with Androsensor:

Results: