$7-19.$ Water flow through the horizontal channel is defined by the stream function $=2(x^2-y^2)\frac{m^2}{s},$ where $x$ and $y$ are in meters. If the pressure at $B$ is atmospheric, determine the pressure at point $A(0\mathrm{.}5m,0)$ and the flow per unit depth in $\frac{m^2}{s}.$

Problem $7-19$