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Someone had posted it on GoIIT long ago but i am still posting it in order to help Newcomers on GoIIT.........

MOMENT OF INERTIA

For linear, or translational, motion an object's resistance to a change in its state of motion is called its inertia and is measured in terms of its mass, in kg. When a rigid body is rotated, its resistance to a change in its state or rate of rotation is called its rotational inertia, which is measured in terms of its moment of inertia, in kg m2. This resistance has a two-fold property:

1. the amount of mass present in the object, and
2. the distribution of that mass about the chosen axis of rotation.

In general, the formula for a single object's moment of inertia is Icm = kmr2 where k is a constant whose value varies from 0 to 1. Different positions of the axis result in different moments of inertia for the same object; the further the mass is distributed from the axis of rotation, the greater the value of its moment of inertia.

That is, the smaller the coefficient of mr2, the easier it is to accelerate the object. That is, spheres accelerate easier than cylinders, which accelerate easier than thin rings or hoops. Since an object's moment of inertia increases as its mass is moved further from its axis of rotation, hoops and rings would represent the greater inertia since all of their mass is concentrated at a constant distance, r, from the center of rotation.

List of Some Common Moment of Inertia

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