mass

in torsional vibrations moment of inertia is a very important determining factor. it is a quantitative measure of the resistance of an object to torsion. it is synonymous to mass in displacement systems. the greater the moment of inertia the lesser the degree of torsional vibrations and vice versa. moment of inertia relates torsional vibrations to the geometry of the part considered irrespective of its composing material and its strength.

The moment of inertia of a hollow cylinder can be calculated with the help of the formula, I=0.5xMxRxR. Here I is inertia, M is mass and R is the radius.

bh^3/36

This is known as parallel axes theorem.

Statement:

If IG be the moment of inertia of a body of mass M about an axis passing through its centre of gravity, then MI (I) of the same body about a parallel axis at a distance 'a' from the previous axis will be given as I = IG + M a2