Fr.: théorème de Steiner
The → moment of inertia of a body about an arbitrary axis x' is equal to the sum of its moment of inertia about axis x, passing through the center of mass of the body and parallel to axis x', and the product of the mass M of the body by the square of the distance d between axes x and x': Ix' = Ix + Md2. Same as → parallel axis theorem.
Named after Jakop Steiner (1796-1863), a Swiss mathematician who derived this statement; → theorem.