(a) Explain how the concepts of friction factor, f, and Reynolds number, Re, are used in conjunction with the Darcy Equation to calculate the pressure drop encountered in flow within a straight circular pipe. Illustrate your answer with a sketch graph of the different relationship between f and Re in the laminar and turbulent flow regimes and explain the basis of these different relationships. [15] (b) Use your knowledge of laminar flow and the Poiseuille Equation to confirm the empirical result f=16/Re in the Moody Plot for the Fanning friction factor. Explain any assumptions you make