20.25 A l-in, 16-BWG copper tube, 10 ft long, has its outside surface maintained at 240 F. Air at 60 F and atmospheric pressure is forced past this tube with a velocity of 40 fps. Determine the heat flux from the tube to the air if the flow of air is a. parallel to the tube b. normal to the tube axis Also answer: c) Qualitatively explain the reason for differences in the answers to a) and b). Consider the average temperature gradients between the air and the surface from the point of initial contact to the end of the contact (i.e., consider differences in the average temperature gradients for flow along the tube vs. over/across the tube)