Water flows around a $6-$ft$-$diameter bridge pier with a velocity of $U=15f\frac{t}{s}.$ Estimate the force $($per unit length$)$ that the water exerts on the pier. Assume that the flow can be approximated as an ideal fluid flow around the front half of the cylinder, but due to flow separation $($see the Video$),$ the average pressure on the rear half is constant and approximately equal to $\frac{1}{2}$ the pressure at point $A($see the figure below$).$