1) What is the physical significance of the Reynolds number? What is the generally accepted value of the Reynolds number above which the flow in smooth pipes is turbulent? 2) Consider the flow of air and water in pipes of the same diameter, at the same temperature, and at the same mean velocity. Which flow is more likely to be turbulent? Why? 3) How does surface roughness affect the pressure drop in a pipe if the flow is turbulent? What would your response be if the flow were laminar? 4) Show that the Reynolds number for flow in a circular pipe of diameter D can be expressed m is the mass flowrate, and the dynamic viscosity as Re = 4m