A cylindrical piece of aluminum at 400C has a length 5 cm, cross-sectional area 1 cm, and is being cooled by air at 20 C. The average convective heat transfer coefficient at all sides is h=300 W/(mK) and the thermal conductivity of aluminum is 240 W/(m K). Its density is 2700 kg/m and its specific heat capacity is 890 J/(kgC). a. Determine the two Biot numbers (radial and axial) associated with this system. What do these values mean? b. How long will it take for the aluminum to reach 40C?