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

A U-tube open at both ends is partially filled with water (Fig. P15.67a). Oil having a density 750 kg/m3 is then poured into the right arm and forms a column L = 5.00 cm high (Fig. P15.67b). (a) Determine the difference h in the heights of the two liquid surfaces. (b) The right arm is then shielded from any air motion while air is blown across the top of the left arm until the surfaces of the two liquids are at the same height (Fig. P15.67c). Determine the speed of the air being blown across the left arm. Take the density of air as constant at 1.20 kg/m3.

A negative pressure of 25.0 atm can sometimes be achieved with the device in Figure 11.44 before the water separates. (a) To what height could such a negative gauge pressure raise water? (b) How much would a steel wire of the same diameter and length as this capillary stretch if suspended from above? Figure 11.44 (a) When the piston is raised, it stretches the liquid slightly, putting it under tension and creating a negative absolute pressure P=F/A (b) The liquid eventually separates, giving an experimental limit to negative pressure in this liquid.

How tall must a water-filled manometer be to measure blood pressures as high as 300 mm Hg?