A 20.0 g copper ring at 0.000°C has an inner diameter of D
= 2.54000 cm. An aluminum sphere at 100.0°C has a diameter of d =
2.545 08 cm. The sphere is put on top of the ring (Fig. 18-35), and the two are allowed to come to thermal equilibrium, with no heat lost to the surroundings. The sphere just passes through the ring at the equilibrium temperature.

What is the mass of the sphere?