Can someone explain something to me ? I refer you to http://www.engineering.com/content/ContentDisplay?contentId=41005050". If we consider the rectangular block to be a cube, Then I would expect that we would get the mass moments of inertia all equal, Ixx = Iyy = Izz. But, in the page I refered you to, if we let a = b = L, then we get Ixx = Iyy, but Izz is different. Can anyone explain why Izz is different from Ixx and Iyy ?