Air enters a 0.8 cm I.D, tube at 20 degree C with an average velocity of 0.8 m/s. The tube wall is kept at 40 degree C. Plot Tb(x) until it reaches 39 degree C. Use properties evaluated at [(20 + 4 0)/2 ] degree C for the whole problem, but report the local error in h at the end to get a sense of the error incurred by the simplification.