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1. A vacuum gauge indicates that the pressure of air in a rigid vessel is 0.2 bar (vacuum). The pressure of the atmosphere is equivalent to 750 mm column of mercury. Given: Density of mercury is 13.59 g/cm3.

i. Sketch the system with appropriate labels. ii. Determine the atmospheric air pressure, in bar. iii. Calculate the absolute pressure of the air in the vessel, in kPa.

(Ans: 1 bar; 80 kPa)

2. A gas is contained in a vertical, frictionless piston-cylinder device, as shown in Figure 1.1. The piston has a mass of 4 kg and cross sectional area of 35 cm2. A compressed spring above the piston exerts a force of 60 N on the piston. If the atmospheric pressure is 95 kPa, determine the absolute pressure inside the cylinder.
(Ans: 123.35 kPa)

Figure 1.1

3. The gage pressure of the air in the tank shown in Figure 1.2 is measured to be 65 kPa. Determine the differential height h2 of the mercury column.

(0.47 m)

Figure 1.2

4. The absolute pressure inside a tank is 0.4 bar and the surrounding atmospheric pressure is 98 kN/m2. What would the reading be on a gauge pressure attached to the tank, in kPa.
[-58 kPa]

5. A barometer reading indicates that the atmospheric pressure is 730mm Hg. Determine the pressure in bar. (Density of mercury is 13600 kg/m3 and earth’s gravity is 9.81 m/s2).
[0.974 bar]

6. A gas with a mass of 15 kg is contained in a vessel whose dimensions are 2 m x 2 m x 2 m. Determine the density of the gas (show the unit).
[1.875 kg/m3]

7. Water at a temperature of 50oC rises by 15oC during a heating process. What would be the change of temperature in K? Determine the percentage increase in temperature.
[15 K, 4.64%]

60 N…...

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