mechanics

Within physics, mechanics is the science of forces and their resulting affects on motion. A basic division is:

• statics - the mechanics of objects not in motion, e.g., why a bridge, a building, a mountain, or a planet does not collapse under its own weight.
• dynamics - the mechanics of moving objects, e.g., an automobile engine's moving parts, a rocket's motion, or the orbits of planets.

A subdivision of dynamics is kinematics, which is the science of motions without regard to what is causing them. The subject of Kepler's laws is the precise motion of orbiting planets, i.e., kinematics, and the subject of Newton's laws is dynamics, which also includes the forces causing these motions. The term celestial mechanics refers to the mechanics of orbiting astronomical objects, which was a scientific question that motivated the development of mechanics.

The term classical mechanics refers to that based upon Newton's Laws, while quantum mechanics deals with what was later discovered regarding the interactions on a very small scale, e.g., the size of atoms and smaller. Statistical mechanics relates mechanics of a huge number of objects to properties of the whole, a primary example being the relationship between the dynamics of individual molecules within a gas to the behavior of the gas as a whole, e.g., the ideal gas law and thermodynamics. The statistics of large numbers explains a surprising amount of physics. Mechanics including relativity (relativistic mechanics) is generally considered part of classical mechanics: though it is new and radical compared to Newton's laws, quantum mechanics represents a more radical alternative, and the term classical mechanics is used to mean other than quantum mechanics. The term Newtonian mechanics is used for classical mechanics, specifically without including relativity.