A spherical container of outer diameter 2.5 m is buried below the wrath’s surface. The distance of the center of the container to the earth surface is 10 m. The container issued to temporarily store radioactive wastes where heat is generated at a rate of 70 W/m3. The soil surface temperature is 15oC and the wall thickness of the container is 10 cm.
What is the controlling resistance for this heat transfer?