A circular fin of rectangular profile is attached to a 3.0-cm-diameter tube maintained at 100C. The outside

Question:

A circular fin of rectangular profile is attached to a 3.0-cm-diameter tube maintained at 100ºC. The outside diameter of the fin is 9.0 cm and the fin thickness is 1.0 mm. The environment has a convection coefficient of 50 W/m2 ∙ ºC and a temperature of 30ºC. Calculate the thermal conductivity of the material for a fin efficiency of 60 percent.