Microsoft Word - Cengel and Boles TOC _2-03-05_.doc

44 | Thermodynamics

1–66 Consider a 1.8-m-tall man standing vertically in water

and completely submerged in a pool. Determine the differ-

ence between the pressures acting at the head and at the toes

of this man, in kPa.

1–67 Consider a U-tube whose arms are open to the atmo-

sphere. Now water is poured into the U-tube from one arm,

and light oil (r790 kg/m^3 ) from the other. One arm con-

tains 70-cm-high water, while the other arm contains both

fluids with an oil-to-water height ratio of 4. Determine the

height of each fluid in that arm.

1–72E Repeat Prob. 1–71E by replacing air by oil with a

specific gravity of 0.69.

1–73 The gage pressure of the air in the tank shown in Fig.

P1–73 is measured to be 80 kPa. Determine the differential

height hof the mercury column.

70 cm Water

Oil

FIGURE P1–67

1–68 The hydraulic lift in a car repair shop has an output

diameter of 30 cm and is to lift cars up to 2000 kg. Deter-

mine the fluid gage pressure that must be maintained in the

reservoir.

1–69 Freshwater and seawater flowing in parallel horizontal

pipelines are connected to each other by a double U-tube

manometer, as shown in Fig. P1–69. Determine the pressure

difference between the two pipelines. Take the density of sea-

water at that location to be r1035 kg/m^3. Can the air col-

umn be ignored in the analysis?

60 cm

10 cm

70 cm

40 cm

Fresh

water

Sea

water

Air

Mercury

FIGURE P1–69

1–70 Repeat Prob. 1–69 by replacing the air with oil whose
specific gravity is 0.72.

1–71E The pressure in a natural gas pipeline is measured by
the manometer shown in Fig. P1–71E with one of the arms
open to the atmosphere where the local atmospheric pressure
is 14.2 psia. Determine the absolute pressure in the pipeline.

10 in

6 in

2 in

25 in

Natural

Gas

Water

Air

Mercury

SG = 13.6

FIGURE P1–71E

Air

30 cm

75 cm

h Mercury

SG = 13.6

Water

Oil

80 kPa SG = 0.72

FIGURE P1–73

1–74 Repeat Prob. 1–73 for a gage pressure of 40 kPa.

1–75 The top part of a water tank is divided into two com-

partments, as shown in Fig. P1–75. Now a fluid with an

50 cm

95 cm

80 cm

Unknown

liquid

WATER

FIGURE P1–75