$2.(20$ pts$)$ You are conducting experiments on an airfoil in a wind tunnel. A manometer connected to a pitot$-$static probe in the wind tunnel's test section measures a differential pressure of $6$ inches of water column. The local static pressure and temperature in the test section are $2040$ psf and $\backslash (515^\{\backslash$circ$\}$ R $\backslash ),$ respectively. $($a$)$ Determine the velocity in the test section. In addition, you measure a pressure of $-4$ inches of water column at a point on the upper surface of the wing. Determine $($b$)$ the pressure coefficient value at this point, and $($c$)$ the speed of the air moving over this point.

The specific gravity of water is $\backslash (62\mathrm{.}4\backslash$mathrm$\{$lb$\}/\backslash$mathrm$\{$ft$\}^\{3\}\backslash )$ and the gas constant of air is $\backslash (1716\backslash$mathrm$\{$ft$\}\backslash$cdot $\backslash$mathrm$\{$lb$\}/\backslash$mathrm$\{$slug$\}\backslash$cdot$\{\}^\{\backslash$circ$\}\backslash$mathrm$\{$R$\}\backslash )$