A pipeline connects 2 reservoirs. The elevation of the upper reservoir is 20 m higher than the elevation of the lower reservoir. The length of the pipeline is 6 km. The flow rate in the pipe is 0.8 m^3/s . The absolute roughness of the pipeline is 2 mm. The sum of the minor loss coefficients is 40.The water temperature is 10 C. Determine the diameter of the pipe.