Families of Portraits of Some Pendulum-Like Systems in Dynamics

Abstract: The so-called pendulum-like systems arise in dynamics of a rigid body ina non-conservative field, in the theory of oscillations, and in theoretical physics. In this article, themethods of analysis are described which allow us to generalize the previous results. Herewith, wedeal with some qualitative questions of the theory of ordinary differential equations whose solutionfacilitates studying some dynamical systems. In result of investigating more general classes ofsystems, we show that these general systems possess the already known family of nonequivalentphase portraits. We also deal with the aspect of integrability. © 2020, Pleiades Publishing, Ltd.