A 21 cm by 30 cm hot surface (500 K) is to be covered by 3 cm diameter pin fins 6 cm long. The fins have an efficiency of 1.0. An air stream at 27 C and flowing at 20 m/s cools the pin fins and the surface. a) What is the temperature of the pin fins? b) How many pin fins can be placed on the hot surface if they are to be separated by 1 cm? c) What is the overall hot surface effectiveness? d) What is the cooling capacity (heat transfer rate) of the finned surface?