Friction factor for flow along a flat plate² 

(a) An expression for the drag force on a flat plate, wetted on both sides, is given in Eq. 4.4-30. This equation was derived by using laminar boundary, layer theory and is known to be in good agreement with experimental data. Define a friction factor and Reynolds number, and obtain the f versus Re relation. 

(b) For turbulent flow, an approximate boundary layer treatment based on the 1/7 power velocity distribution gives F_k = 0.072pv²_∞WL (Lv_∞p/µ) p/µ when 0.072 is replaced by 0.074, this relation describes the drag force within experimental error for 5 x 10⁵ < Lv_∞p/µ < 2 x 10⁷. Express the corresponding friction factor as a function of the Reynolds number.