at the beginning of a dive (when it is full of air) and at the end of a dive (when it no longer contains any air). 40.(III) A 3.65-kg block of woodfloats on water.What minimum mass of lead, hung from the wood by astring, will cause the block to sink? 41.(I) A 12-cm-radius air duct is used to replenish the air of aroomevery 12 min. How fast doesthe air flow in the duct? 42. (I) Calculate the average speed of blood flow in the major arteries of the body, which have a total cross-sectional area of about Use the data of Example 10 – 12. 43.(I) How fast does water flow from a hole at the bottom of a very wide, 4.7-m-deep storage tank filled with water? 44. (I) Show that Bernoulli’s equation reduces to the hydro- static variation of pressure with depth (Eq. 10 – 3b) when there is no flow 45.(II) What is the volume rate of flow of water from a1.85-cm-diameter faucet if the pressure head is 12.0 m? 46.(II) A fish tank has dimensions 36 cm wide by 1.0 m longby 0.60 m high. If the filter should process all the water inthe tank once every 3.0 h, what should the flow speed be in the 3.0-cm-diameter input tube for the filter? 47.(II) What gauge pressure in the water pipes is necessary ifa fire hose is to spray water to a height of 16 m? 48. (II) A (inside) diameter garden hose is used to fill a round swimming pool 6.1 m in diameter. How long will it take to fill the pool to a depth of 1.4 m if water flows from the hose at a speed of 49. (II) A wind blowing over the flat roof of a house causes the roof to lift off the house. If the house is in size, estimate the weight of the roof. Assume the roof is not nailed down. 50.(II) A 6.0-cm-diameter horizontal pipe gradually narrowsto 4.5 cm. When water flows through this pipe at a certainrate, the gauge pressure in these two sections is 33.5 kPaand 22.6 kPa, respectively. What is the volume rate of flow? 51. (II) Estimate the air pressure inside a category 5 hurricane, where the wind speed is (Fig. 10 – 52). 300 km h 6.2 m * 12.4 m 180-km h 0.40 m s? 5 8 -in. A v 1 = v 2 = 0 B . 2.0 cm 2 . 8.2 m * 5.0 m * 3.5 m ( SG = 0.50 )
h 16 m P 3.8 atm Faucet 288 CHAPTER 10 Fluids 52.(II) What is the lift (in newtons) due to Bernoulli’s princi-ple on a wing of area if the air passes over the topand bottom surfaces at speeds of and respectively? 53. (II) Water at a gauge pressure of 3.8 atm at street level flows into an office building at a speed of through a pipe 5.0 cm in diame- ter. The pipe tapers down to 2.8 cm in diameter by the top floor, 16 m above (Fig. 10 – 53), where the faucet has been left open. Calculate the flow velocity and the gauge pressure in the pipe on the top floor. Assume no branch pipes and ignore viscosity. 0.78 m s 150 m s, 280 m s 88 m 2 *10–11 Viscosity *58. (II) A viscometer consists of two concentric cylinders, 10.20 cm and 10.60 cm in diameter. A liquid fills the space between them to a depth of 12.0 cm. The outer cylinder is fixed, and a torque of keeps the inner cylinder turning at a steady rotational speed of What is the viscosity of the liquid?
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