As indicated in Fig. P9.97, the orientation of leaves on a tree is a function of the wind speed, with the tree becoming "more streamlined" as the wind increases. The resulting drag coefficient for the tree (based on the frontal area of the tree, \(H W\) ) as a function of Reynolds number (based on the leaf length, \(L\) ) is approximated as shown. Consider a tree with leaves of length \(L=0.3 \mathrm{ft}\). What wind speed will produce a drag on the tree that is 6 times greater than the drag on the tree in a \(15 \mathrm{ft} / \mathrm{s}\) wind?

Figure P9.97

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0.6 0.5 U 0.4 Calm wind Strong wind 0.3 0.2 U 0.1 w 0 10,000 100,000 1,000,000 Re=pUL