Definition of Mass Moment of Inertia
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Mass Moment of Inertia

The Mass Moment of Inertia of a solid measures the solid's ability to resist changes in rotational speed about a specific axis. The larger the Mass Moment of Inertia the smaller the angular acceleration about that axis for a given torque.

The mass moment of inertia depends on a reference axis, and is usually specified with two subscripts. This helps to provide clarity during three-dimensional motion where rotation can occur about multiple axes.

Following are the mathematical equations to calculate the Mass Moment of Inertia:

 where x is the distance from the yz-plane to an infinitesimal area dA. y is the distance from the zx-plane to an infinitesimal area dA. z is the distance from the xy-plane to an infinitesimal area dA.