8.39 Hydraulic mining is to be done using water from a lake located 300 m above the mine site. A 900 m long fire hose with an inside diameter of 75 mm and a relative roughness of 0.01 will be used.

Couplings are located every 10 m along the hose. The nozzle outlet diameter is 25 mm and its loss coefficient is 0.04 based on the upstream velocity. Estimate the maximum outlet velocity from the hose and the maximum force exerted on a rock face by the water jet.