$9\mathrm{.}4\mathrm{.}3.$

A streamlined train has a length of $280$ ft$,$ the side surfaces are $8\mathrm{.}5$ ft high, and the top is $8$ ft wide. Calculate the power required to overcome frictional drag as the train moves at $90$ mph through

the standard atmosphere at sea level. Assume that the drag on the top and side surfaces is equal to the drag on one side of a single flat plate $25$ ft wide and $280$ ft long.