An experimental device that produces excess heat is passively cooled. The addition of pin fins (cylindrical fins) to the casing of this device is being considered to augment the rate of cooling. Consider a copper pin fin 0.25cm in diameter that protrudes from a wall at 95degC into ambient air at 25degC. The natural convection coefficient of the air is 10 W/m2-K. Calculate the heat loss assuming first that the fin is infinitely long, then assuming the fin is 2.5cm long and the coefficient at the end is the same as around the circumference. How long would the fin have to be for the infinitely long solution to be correct within 5%