Stability and bifurcation of equilibrium of a body containing a liquid

Taking the physical pendulum as an example, it is shown how the evolution of bifurcation and change of stability of different equilibrium positions occur. A series of problems is given about the stability of equilibrium as stationary motion of a vessel with capillary liquid. The aim of each example is to introduce some new mechanical property, introduced into the problem by surface force. Different definitions of stability equilibrium and stationary movement of a body with a liquid are discussed and compared, which reflect the specific case of one or the other problem.