The rear window of an automobile is defogged by passing warm air over its inner surface.

(a) If the warm air is at T_∞,i = 40°C and the corresponding convection coefficient is hi = 30 W/m² ∙ K, what are the inner and outer surface temperatures of 4-mm-thick window glass, if the outside ambient air temperature is T_∞,0 = - 10°C and the associated convection coefficient is ho = 65 W/m 2 . K?

(b) In practice T_∞,0 and h_o vary according to weather conditions and car speed. For values of h_o = 2, 65, and 100 W/m².∙ K, compute and plot the inner and outer surface temperatures as a function of T_∞,0 for – 30 ≤ T_∞,0 ≤ O°C.