Liquid water enters a manifold (series of pipes) at 1080 psi and 125 °F with a mass flow rate of 3.5 x 10 6 lb /hr and flows through a number of one inch diameter tubes. At steady state, how many tubes are needed if the velocity in each tube must be less than 15 ft/s? Assume the water is at constant density as it flows throughout the manifold and that the cross-sectional area of the pipes is circular.