Biological systems exhibit strong dynamic variations; for example, a system may have a tendency towards either a steady state, periodic behaviour or chaotic oscillations. These findings, explained by dynamic systems theory, have allowed researchers to formally relate a wide variety of systems, such as the theory of rumour propagation, glucose…

This note gives the solution to the motion of a perfectly hard ball that was launched against a perfectly hard inclined plane. The solution comprises recurrent formulas that give the parts of the trajectory between the impacts, which are parabolas. In the upward part of the motion, the parabolas become higher and narrower, in the downward part…