Progressive Motions in a Fluid of a Body Controlled by an Internal Force

The progressive motions of a rigid body containing an internal mobile mass and controlled by the force of its interaction with this mass are considered. The body moves within a fluid, and its resistance force is proportional to the squared velocity of the body and depends on the direction of motion. The corresponding trajectories are obtained and it is shown that they approach periodic motions. The average velocity of the system depending on its parameters is evaluated.