Excerpt from Mechanics and Hydrostatics: For Beginners The first portion will treat of the action of forces on bodies, the forces being so arranged that the bodies are at rest. This is the subject of Statics. The second portion will deal with the action of forces on bodies in motion. This is the subject of Dynamics. The third portion will deal with the properties of liquids and gases and of the effect of forces on them when they are at rest. This is the subject of Hydrostatics. The title Dynamics is often used to include all three of these subdivisions