The medallion shown in Figure P6.79 has been made by cutting a small circular piece out of a larger circular disk. The diameter of the original disk is twice the diameter of the hole, and the thickness of the disk is uniform. You begin to wonder about the location of the center of mass of this object, but the calculation seems impossibly difficult. Then you visualize two circular pieces coming together in superposition. Where is the center of mass?

Data from Figure P6.79