The wheels of a wagon can be approximated as the combination of a thin outer hoop of radius rh=0.156 m and mass 5.08 kg, and two thin crossed rods of mass 8.23 kg each. Imagine replacing the wagon wheels with uniform disks that are td=5.25 cm thick, made out of a material with a density of 6910 kg/m^3.
If the new wheel is to have the same moment of inertia about its center as the old wheel about its center, what should the radius of the disk be?