The interpretation of complex trajectories of rigid bodies by the identification of their centre of
mass (CM), has a large potential for improving the understanding of the concept of CM at college and
university level. Therefore, it is not surprising that there are several techniques described in the
literature concerning how to identify the CM of rigid bodies. However, these techniques fail when
the CM’s position in the body’s frame of reference changes when the body is at motion. In this work
we present a computational model that allows the identification of the CM with very good accuracy,
either when the CM’s position changes or is fixed in the body’s frame of reference. This model can
be used for a system of bodies moving in a plane, for which the CM of each body coincides with its
geometric centre. The effectiveness of this model is tested with experiments using video acquisition
and numerical analysis, and can be done in experimental classes under controlled conditions. St…