A well is being drilled at a depth of 5,000 ft using water having a density of 8.33 lbm/gal and a viscosity of 1 cp as the drilling fluid. The drillpipe has an external diameter of 4.5 in, and an internal diameter of 3.826 in. The diameter of the hole is 6.5 in. The drilling fluid is being circulated at a rate of 500 gal/min. Assume a relative roughness of zero. a. Determine the flow patterm in the drillpipe. Answer: turbulent. b. Determine the frictional pressure loss per 1,000 ft of drillpipe. Answer: 51.3 psi/1,000 ft. c. Determine the flow pattern in the annular op- posite the drillpipe. Answer: turbulent. d. Determine the frictional pressure loss per 1,000 ft of annulus. Answer: 72.9 psi/1,000 ft.