The heat transfer coefficient for air flowing over asphere is to be determined by observing temperature-time history of a sphere fabricated from pure copper. The sphere, which is 12.7 mm in diameter, is at 66oC before it is inserted into an airstream having a temperature of 27oC. A thermocouple on the outer surface of the sphere indicates 55oC 69 s after the sphere is inserted. (a) Assume and then justify that the sphere behaves as spacewise isothermal object. (b) Calculate the heat transfer coefficient, h. (c) Calculate the amount of heat lost by the sphere during this time, i.e., 69 s.
