A $42$ meter bilboard is supported by two cyindrical poles $(2m$ long $),$ each having a diameter of $200$ mm $.$ A uniform $3\frac{m}{s}$ wind is blowing parallel to the bliboard. The ambient temperature is $21\mathrm{.}85C$

a$.$ Determine the total drag force of the bilboard system. Assume that the flow over the downwind mast is not infuenced by the presence of the upwind mast. Tip: Divide the system into three parts. namely a flat ptate and wo smooth cylindrical masts

b$.$ determine the distance along the bilboard where transition occurs

c$.$ determine the layer thickness on the board at the point of transtion and at the end of the board.