Extracted text: What is the roughness coefficient of a steel pipe with a length of 100 meters if the observed head loss was 15 m, friction factor is 0.0843 and relative roughness is 600 wherein the observed flow is laminar. Water at 160°F is flowing at 30.0 ft/s and has a kinematic viscosity of 4.38 x 10-6 ft2/s.