(Solved): A very long copper rod 20 mm in diameter extends horizontally from a plane heated wall maintained ...

A very long copper rod 20 mm in diameter extends horizontally from a plane heated wall maintained at 100°C. The surface of the rod is exposed to an air environment at 20°C with convective heat transfer coefficient of 8.5 W/m²-deg. Workout the heat loss if the thermal conductivity of copper 400 W/m-deg. Further estimate how long the rod be in order to be considered infinite. is