12.43 ⚫ What gauge pressure is required in the city water mains for a stream from a fire hose connected to the mains to reach a vertical height of 15.0 m? (Assume that the mains have a much larger diameter than the fire hose.) P₁ + pgy₁ + 1/2 pv₁² = p₂+ pgy2 + 1/2 pv₂² Larger diameter means negligible speed V₂ = 0; P₂ = = atoms Y₁ = 0; y₂ = 15.0 m; v₁ = 0; v₂ = 0 Gauge pressure = ? Y2 1.47x105 Pa

Water supplied to a house by a water main has a pressure of 3.00105N/m2 early on a summer day when neighborhood use is low. This pressure produces a flow of 20.0 L/min through a garden hose. Later in the day, pressure at the exit of the water main and entrance to the house drops, and a flow of only 8.00 L/min is obtained through the same hose. (a) What pressure is now being supplied to the house, assuming resistance is constant? (b) By what factor did the flow rate be water main increase in order to cause this decrease in delivered pressure? The pressure at the entrance of the water main is 5.00105N/m2 , and the original rate was 200 L/min. (c) How many more users are there, assuming each would consume 20.0 L/min in be morning?

Considering the magnitude of typical arterial blood pressures, why are mercury rather than water manometers used for these measurements?

(a) How high will water rise in a glass capillary tube with a 0.500-mm radius? (b) How much gravitational potential energy does the water gain? (c) Discuss possible sources of this energy.