How Do You Calculate the Total Inertia Matrix for a Composite Object?

[ang__]

Homework Statement

The object is made out of multiple parts. The inertia matrices of every part are given. Only one part is rotating. How do I find the total inertia matrix.

Homework Equations

The Attempt at a Solution

I thought that I could sum the inertia matrices, after tranforming them to global coordinates.[/B]

 

[Dr.D]

Inertia is additive. Mass terms are simply added. Moments of inertia are combined using the parallel axis theorem.