8. A piece of solid copper and a piece of solid lead are placed in an insulated and evacuated (no air) container. They do not touch each other.
The piece of copper has an emissivity of 0.0400. The copper is formed into a sphere with a radius of 3.15 cm and a mass of 1.165 kg at a temperature of 555 $^\circ$C.
The piece of lead has an emissivity of 0.0600 and a coefficient of linear expansion of $2.9 \times 10^{-5} K^{-1}$. The lead is formed into a rod with a radius of 0.945 cm and a length of 85.6 cm and a mass of 2.714 kg at -55.5 $^\circ$F.
a. Explain, in words, what happens to the temperature of each of the metals over time. Explain how and why that happens.
b. What is the initial net heat current from radiation for the copper?
c. Once the system reaches thermal equilibrium, what is the temperature of the lead?
d. What is the change in volume of the copper sphere from the initial conditions to equilibrium?
e. What is the change in length for the lead rod from the initial conditions to equilibrium?