Hi Folks, I am designing a piece of kinetic scultpure that will involve cubes made from aluminium square tubing rotating around an axis that passes through two diagonal corners. I am trying to determine motor size to drive this thing, and to do that I need to know its moment of inertia. Math is not a strong point for me AT ALL. I don't even know what the symbols in the calcualtions for determining moment of inertia simple shapes represent. So while I would like to understand the calculation I'd request that I am not bamboozled by the theory. So lets begin. Lets say my material has a mass of Q per meter. The cube side has a length of L. Most confounding for me (as I have not found an example of this elsewhere) the axis of rotation passes through two diagonal corners. So lets say a cube L of 1000mm and the tubing is 50mm x 50mm (not sure if this is important) The axis of rotation is the thin light grey line in the next image.. [URL]http://fle33.com/uploads/mi_cube.jpg[/URL] Any help is greatly appreciated.