statics, branch of mechanics concerned with the maintenance of equilibrium in bodies by the interaction of forces upon them (see force). It incorporates the study of the center of gravity (see center of mass) and the moment of inertia. In a state of equilibrium all the forces acting on a body are exactly counterbalanced by equal and opposite forces, thus keeping the body at rest. The principles of statics are widely applied in the design and construction of buildings and machinery.