An atmospheric boundary layer is formed when the wind blows over the Earth's surface.Typically, such velocity profiles can be written as a power law: u = ayn, where the constants a and n depend on the roughness of the terrain.As is indicated in Fig. P9.22, typical values are n= 0.40 for urban areas, n = 0.28 for woodland or suburban areas, and n = 0.16 for flat open country (Ref. 23). (a) If the velocity is 20 ft/s at the bottom of the sail on your boat (y = 4 ft),what is the velocity at the top of the mast (y =30 ft)? (b) If the average velocity is 10 mph on the tenth floor of an urban building, what is the average velocity on the sixtieth floor?

Fig: 1

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