A \(20-\mathrm{m} / \mathrm{s}\) wind blows against a \(20-\mathrm{m}\)-tall, \(0.12-\mathrm{m}\)-diameter flag pole.

(a) Determine the anchoring moment at the base of the pole.

(b) Determine the anchoring moment if a \(2-\mathrm{m}\) by \(2.5-\mathrm{m}\) flag is attached to the top of the pole. See Fig. 9.32 for drag coefficient data for flags.

Fig. 9.32

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Shape Reference area Parachute Frontal area A-D Drag coefficient CD 1.4 Porosity 0 0.2 0.5 Porous Frontal area 1.42 1.20 0.82 parabolic dish A =D 0.95 0.90 0.80 Porosity = open area/total area Standing CDA = 9 ft Average Sitting CDA = 6 ft person Crouching CDA = 2.5 ft Fluttering flag A = (D 1723 CD 0.07 0.12 0.15 Empire State Building Frontal area 1.4 Frontal area 1.8 Six-car passenger train Bikes Upright commuter A = 5.5 ft 1.1 Racing A = 3.9 ft 0.88 Drafting A = 3.9 ft 0.50 Streamlined A = 5.0 ft 0.12 Tractor-trailer trucks Standard Frontal area 0.96 Fairing With fairing Frontal area 0.76 Gap seal With fairing and Frontal area 0.70 gap seal Tree U = 10 m/s U = 20 m/s U = 30 m/s Frontal area 0.43 0.26 0.20 Dolphin Wetted area Large birds Frontal area 0.0036 at Re = 6 x 106 (flat plate has CD = 0.0031) 0.40