Consider a refrigeration truck traveling at 55 mph at a location where the air temperature is 80 F. The refrigerated compart- ment of the truck can be considered to be a 9-ft-wide, 8-ft-high, and 20-ft-long rectangular box. The refrigeration system of the truck can provide 3 tons of refrigeration (i. e., it can remove heat at a rate of 600 Btu=min). The outer surface of the truck is coated with a low-emissivity material, and thus radiation heat transfer is very small. Determine the average tempera- ture of the outer surface of the refrigeration compartment of the truck if the refrigeration system is observed to be operating at half the capacity. Assume the air ow over the entire outer surface to be turbulent and the heat transfer coecient at the front and rear surfaces to be equal to that on side surfaces. For air properties evaluations assume a lm temperaturea of 80 F. Is this a good assumption?