Mechanics is a science that studies the effects of forces on solids, liquids, and gases at rest or in motion. Engineers use mechanics to determine stresses and deformations in machine parts, such as gear teeth, and in structural elements, such as support columns. The principles of mechanics are used by engineers to design products that range in size from tiny computer parts to huge dams; by astronomers to predict the motion of stars, planets, and other celestial bodies; and by physicists to study the motion of atomic particles.
Mechanics can be divided into two branches: statics and dynamics. Statics studies bodies at rest, or in motion at a constant speed and in a constant direction. Dynamics is the study of bodies that undergo a change of speed or direction, or both, when forces act upon them.
Solid mechanics is the study of the motions of rigid bodies and deformable solid bodies, and of the forces that cause such motions. Continuum mechanics deals with deformable bodies. Deformable bodies are gases, liquids, and deformable solids. Areas of specialization in continuum mechanics include theory of elasticity, the study of the reversible deformation of solids; theory of plasticity, the study of the permanent deformation of solids; fluid dynamics, the study of fluids in motion; aerodynamics, the study of gases in motion around a body; and hydraulics, the study of liquids at rest or in motion.
