$4\mathrm{.}6\mathrm{.}21$ Air is drawn into a wind tunnel used for testing automobiles, as shown in Fig. P$4\mathrm{.}6\mathrm{.}21.($a$)$ Determine the manometer reading, $h,$ when the velocity in the test section is $97$ kmph $.$ Note that there is a $0\mathrm{.}025$ m column of oil on the water in the manometer. $($b$)$ Determine the difference between the stagnation pressure on the front of the automobile and the pressure in the test section.

FIGURE P$4\mathrm{.}6\mathrm{.}21$