A machine is a device which receives energy in some available form and utilizes it to do some particular type of work. The theory of machine may be defined as that branch of Engineering science, which deals with the study of relative motion between the various parts of a machine and forces which act on them. The knowledge of theory of machine is very essential for an engineer in designing the various parts of a machine.
The theory of machine may be sub-divided into the following four branches:
1. Kinematics: It is that brands of theory of machines which deals with the relative motion between the various parts of the machines.
2. Dynamics: It is that branch of theory of machines which deals with the forces and their effects, while acting upon the machine parts in motion.
3. Kinetics: It is that branch of theory of machines which deals with the inertia forces which arise from the combined effect of the mass and motion of the machine parts.
4. Statics: It is that branch of theory of machines which deals with the forces and their effects while the machine parts are at rest. The mass of the parts is assumed to be negligible.