where ZZ and GG are parallel axes, GG goes through the CG of the body or assembly, m is the mass of the body or assembly, and dis the perpendicular distance between the parallel axes. This property is most useful when computing the moment of inertia of a complex shape which has been broken into a collection of simple shapes as shown in Figure 10-2a which represents a simplistic model of a mallet. The mallet is broken into two cylindrical parts, the handle and the head, which have masses mh and md, and radii rh and rd, respectively. The expressions for the mass moments of inertia of a cylinder with respect to axes through its CG can be found in Appendix C and are for the handle about its CG axis HH: