Rotational Motion of a body is a motion in which the body moves about a given Axis of Rotation in such a way that all its particles move in different circles, with their centers lying on the Axis of Rotation. Thus Rotational motion can be considered as an integration of several circular motions of elemental masses in the body.
Circular Motion is the motion which is
defined for a point mass or a body of which dimensions are very small compared
to the radius of the circular motion. In case of Rotational Motion, we discuss
extended bodies moving in different orientations about different possible axes
of rotations.
See the video below to understand basic
understanding of Rotational Motion –
The first thing we study in translational
motion is ‘Inertia’ which causes change in state of motion. Similar property used
in rotational motion is ‘Moment of Inertia’, which is the first and most
important parameter used in understanding and defining various other properties
of Rotational Motion. So first we need to discuss about Moment of Inertia of a
particle moving in circular motion and we will extend this knowledge in
calculation of Moment of Inertia of an extended body in rotational motion. See
the video below for Moment of Inertia –