Momental Ellipsoid

Useful geometrical interpretation about an axis; first used by Cauchy. A ume any fixed point, O, in the body, and let a radius vector, OQ, move in such a manner and be of such length that the moment of inertia about OQ may be proportional to the inverse square of the length. Under these circumstances the locus ofQ is always an ellipsoid, and is called the momental ellipsoid. It may be defined by the geometrical property that any radius vector is equal to some constant divided by the square root of the moment of inertia about that radius vector.