1. The problem statement, all variables and given/known data Half disk, radius R, mass m. I need the inertia tensor about the center of mass and then find the Principal moments of inertia about another coordinate system. Struggling with the product of inertia. https://dl-web.dropbox.com/get/Public/Captura%20de%20pantalla%20de%202014-11-24%2001%3A39%3A45.png?_subject_uid=1095356&w=AACECjyEV4pBdqLhSXXGSMtL5WXwAK8nETA8TGnww5IDfQ 2. Relevant equations Concept question. 3. The attempt at a solution I already have the mass products of inertia and the xy product of inertia (all about the center of mass) but my big problem is the product of inertia xz ¿How do I find it? ¿Is it zero? Products of inertia hold information about the symmetry of the object, a bunch of zeros doesn't seem to be a good answer for this. Thanks for your time.