Embodied experiences of the equivalence principle and the temptation of inertial forces

by Andreas Isacsson (Chalmers University of Technology, Göteborg), Ann-Marie Pendrill (University of Gothenburg & Lund University)

Wednesday 20 Jan 2027, 10:00 → 11:00 Europe/Zurich

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From the big bang to black holes, from elementary particles and the fundamental interactions that govern our universe to the world's largest and most complex scientific instruments, our knowledge of the world builds on modern physics. To make our current-best understanding available to all, we need to invest in educational research and bridge the gap between those who know science, those who teach science, and those who learn science. 

This month, we will discuss a paper by Andreas Isacsson, Ann-Marie Pendrill and Linus Sundberg

 

Abstract: 

According to the equivalence principle, acceleration cannot be distinguished from a gravitational field in the opposite direction. Although conceptually different, using inertial forces in a consistent way gives mathematically equivalent descriptions of the interactions required for acceleration. However, we find that while most new students have learned to avoid ‘centrifugal forces’, many of them are still tempted to draw or choose force diagrams including an outward force in some cases of circular motion, but referring to a ‘centripetal force’, and many others prefer a diagram with a centripetal force as a real force. Invoking the weak equivalence principle, which applies to objects with mass, can be a way to connect students’ bodily understanding with formal mechanics. In this way embodied experiences of acceleration during everyday life, sports and play can be used as resources for conceptual understanding. Including kinetic diagrams in the construction of free-body diagrams is a reminder that force equilibrium does not apply for accelerating bodies. The weak equivalence principle is a consequence of classical mechanics. It inspired Einstein to develop the general theory relativity. 

Paper:

Isacsson, A., Pendrill, A.-M., & Sundberg, L. (2026). Embodied experiences of the equivalence principle and the temptation of inertial forces. Eurasia Journal of Mathematics, Science and Technology Education, 22(7), em2872. https://doi.org/10.29333/ejmste/18964