A U.S. flag waves majestically atop a flagpole on a blustery day
in March. The flagpole is 45 ft high, and the flag measures 4.0 ft
x 7.6 ft. I. Estimate the drag force on the flag in a 28 mph wind,
based on (a.) a calculation of skin friction drag only, with the
flag behaving as a rigid, thin flat plate, and (b.) using an
experimentally determined drag coefficient for a model flag tested
at dynamically similar conditions, equal to 0.12. In both cases,
neglect the effect of the flagpole wake, which would reduce the
drag on the flag. II. Calculate the moment at the base of the
flagpole, treating the flagpole as a smooth cylinder, with a
diameter equal to 5.0 in. For this calculation, use the greater of
the results from part I. to estimate the drag force on the
flag.