Q5. (20 marks) A hollow sphere of inner radius r1 = 30 cm and outer radius r2 = 50 cm is heated at the inner surface. Th

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Q5. (20 marks) A hollow sphere of inner radius r1 = 30 cm and
outer radius r2 = 50 cm is heated at the inner surface. The rate of
heat flow out of the sphere is 11.30 kW. The temperature at the
inside and outside surfaces of the sphere is T1 and T2. The thermal
conductivity of the material is k = 170 W(m.K)-1 . (a) Demonstrate
that the rate of heat conduction is computed by the formula: 1 2 1
2 2 1 4 T T P kr r r r     . (b) Find the difference of
temperature between two surfaces of the sphere