A 5 cm diameter radioactive sphere at steady state generates a total of 40 W of thermal energy. The sphere is covered by a layer of insulation 27.5 cm thick so that the total outside diameter is 60 cm The thermal conductivity of the radioactive material is 4.0 W/(mK) . The thermal conductivity of the insulation is 0.5 W/(mK). The insulated sphere is surrounded by a gas at 25 C with a convective heat transfer coefficient of 20 W/(m2K). Compute the temperatures at the following points: (a) Outside insulation surface. (b) Interface between radioactive material and insulation. (c) Centre of radioactive sphere The volume of a sphere is V = 43 r3 and the surface area of a sphere is A = 4r2