On Oct 29, 2012 Hurrcane Sandy Flooded the Holland Tunnel that passes Under the Hudson River! The Tunnel has two tubes: One is 8558 feet long And the other is 8371 feet long Both are 12.5 feet high by 20 feet wide! => (8558 + 8371)*20*12.5 = 4,232,250 Cubic Feet of Water Let's assume you want to pump this water out in 72 hours (or 3 days). If your pumps have six inch diameter pipes and can Pump at a pressure of 50 psi, How many pumps will you need to empty these Tunnels in 72 hours? The Volume of water for a 6 inch pipe at 50 psi Equals 9.5448*D*D*(SqRt(P)) => 9.5448*(1/2)*(1/2)*(SqRt(50)) => 16.872982 Cubic Feet per Second Where P = Pressure = psi And D = Pipe Diameter in feet = 1/2 foot Water Speed = V = SqRt(2*g*h) Where g = 32 ft/s/s and h = feet depth => V = 8*(SqRt(h)) since 2*g = 64 And Water Pressure k = 62.4/144 psi per foot depth => If P = 50 psi => Convert psi to Height of Water Column that results in 50 psi => (144/62.4)*50 = Height of Water Column to Create 50 psi => h = 115.38 Feet Area of Pipe = (((Pi)*D*D)/4) And V = 8*(SqRt(h)) = Speed => (((Pi)*D*D)/4)*8*(SqRt((144/62.4)*P) Equals the flow rate = CubicFeet per Second => 9.5448*D*D*(SqRt(P)) CubicFeet per Second 
Water emerges from a fire hose
at 64 ft/sec. If the rate of
the flow is 180 gallons/minute, find the horse power of the pump motor if the efficiency of the pump is 50%. Also, find the force to hold the fire hose. 
