Bounded by the statements of Feynman and Galileo, I describe certain tricks that can be useful for the teaching of physics. In particular, I describe the calculation of the center of mass (centroid) of an arc of circumference and a circular sector. For this purpose, I also use Pappus’s theorems. An Appendix is available with Archimedes’ method to calculate the volume of a sphere circumscribed by a cylinder.

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Readers can access the Appendix at TPT Online at https://doi.org/10.1119/5.0064624, under the Supplemental tab.
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Supplementary Material

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