Moment of gyration
The moment of gyration represents a characteristic magnitude for "rotational inertia"of a rigid body, such as the rotating assembly of a centrifugal pump or drive (see Starting method). It is designated and calculated by means of mD2 from the mass (m) of the rotating body and the diameter of gyration (D). The unit is kg m2. The diameter of gyration is:
The moment of gyration (mD2) is often replaced by the moment of inertia (J).