10. What natural processes would affect pipe roughness? 11. Water at 20 C is flowing in a pipe of radius 1.0 cm. The viscosity of water at that temperature is 1.005 cp. If the flow speed at the center is 0.200 m/s and the flow is laminar, find the pressure drop along a 5 mm section pipe. 12. A cast iron pipe of equilateral triangular cross section with side length of 20.75in has water flowing through it. The flow rate is 6000gpm and the friction factor for the pipe is 0.017. What is the pressure drop in Ibf/ft? in a 100 foot section? 13. A liquid with specific gravity of 4.7 and a viscosity of 1.3 cp flows through a smooth pipe of unknown diameter, resulting in a pressure drop of 0.183 psi for 1.73 mi. What is the pipe diameter in inches if the mass flowrate is 5900 lb/hr