Abstract
The results of experimental and theoretical studies are presented for the case when the vessel with water performs periodic reciprocating and oscillatory movements. The problem was solved in the linear approximation using the potential equation. From the results of experiments and an analytical analysis of the problem it follows that the first resonance frequency of the oscillation of a liquid in a vessel plays an important role in the character of the motion. At the same time, bifurcation occurs in the region of resonant frequencies, i.e. transitions from the plane motion of the liquid to the rotational motion and vice versa.