For each part in an assembly, the mass moment of inertia matrix is used when you calculate Motion Analysis motion studies. This matrix plays the same role for rotary motion as that played by mass for linear motion.
The mass moments of inertia are the unique components of the symmetric mass moment of inertia matrix. Six mass moments of inertia values are required for this matrix: one each for the moments along the X, Y, and Z axes of the part coordinate frame, and three cross-component terms XY, YZ, and XZ. These values are automatically computed based on the geometry of the sketch block. If you have this data, you can modify the default values in the Mass Moments of Inertia dialog box.
To open this dialog box:
From a Motion Analysis motion study for a layout sketch, select 
, select a block, and click Moments of Inertia for Mass Properties in the Block PropertyManager.
Mass Moments of Inertia
Modify the six mass inertia moments and cross moments: