It is defined as that of engineering science in which deals with the study of relative motion in various parts of the machine and force which acts on them.

Dynamics of Machine
It is the branch of theory of machine in which it deals about the forces and their effects while upon the machine parts in motion
Kinematics of Machine
It is the branch in which deals with the relative motion between various parts of the machine.
Mechanism
A combination of number of bodies assembled in such a way that the motion of one causes constrained and predictable motion to the other is known as Mechanisms.
Function of mechanism to transmit and modify the motion.
Machine
A mechanism or number of mechanism which apart from of imparting definite motion to the parts also transmit and modifies the available mechanical energy into some kind of desired work is known as Machine.
Types of Constrained Motion
- Completely Constrained Motion
- Incompletely Constrained Motion
- Successfully Constrained Motion
1. Completely Constrained Motion
When the motion between pair is limited to a direction irrespective of the direction of force applied, then the motion is said to be Completely Constrained Motion.
Example : Square rod in a square hole
