Mass moment inertia of object displaced from axiz

PTC

Hey y'all,

A plea for general advice here as I embark on a project. Say I have an object rotating around an axis but *displaced* some distance "r" from that axis. It's length, a dimension perpendicular to the axis, is "a." I'm interested in finding the mass moment of inertia for the object. As I see it, I have two choices: (1) develop an integral describing the mass distribution of the object around the axis and then use the fundamental theorem and the interval r to r+a or; (2) use the parallel axis theorem, that is, develop definitive integrals describing both the mass distribution of the object at r=0 and around the axis at r->r+a, summing the two. So real simply, fundamental theorem or parallel axis theorem?

Thanks!

PTC

BruceW

I never really got my head round the parallel axis theorem, so I would use 1), which should be fairly easy, since the object is pointing straight away from the axis, it makes the integral fairly simple.

PTC

Thanks, Bruce! That's just about what I figured--it'd be much easier to compute over the interval. Thanks again!

PTC