BMCT 2123 THERMODYNAMICS ITUTORIAL 01

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FACULTY OF MECHANICAL ENGINEERINGBMCT 2123 THERMODYNAMICS I

TUTORIAL 01

1. What is the difference between the classical and the statistical approaches tothermodynamics?

2. An office worker claims that a cup of cold coffee on his table warmed up to 80oC bypicking up energy from the surrounding air, which is at 25oC. Is there any truth to hisclaim? Does this process violate any thermodynamics laws?

3. What is the difference between the macroscopic and microscopic forms of energy?4. What is the difference between intensive and extensive properties?5. Define the isothermal, isobaric, and isochoric processes.6. What is the difference between gage pressure and absolute pressure?7. Most of the energy generated in the engine car is rejected to the air by the radiator

through the circulating water. Should the radiator be analyzed as a closed system or andopen system? Explain.

8. A can of soft drink at room temperature is put into the refrigerator so that it will cool.Would you model the can of soft drink as a closed system or an open system? Explain.

9. What is the zeroth law of thermodynamics?10. What is a quasi-equilibrium process? What is its importance in engineering?

11. A vacuum gage connected to a tank reads 30 kPa at a location where the barometricreading is 755 mm Hg. Determine the absolute pressure in the tank.Take Hg = 13590 kg/m3.

12. The barometer of a mountain hiker read 930 mbar at the beginning of a hiking trip and780 mbar at the end. Neglecting the effect of altitude on local gravitational acceleration,determine the vertical distance climbed. Assume an average air density of 1.20 kg/m3

and take g=9.7 m/s2.

UNIVERSITI TEKNIKAL MALAYSIA MELAKAKARUNG BERKUNCI 1200

AYER KEROH75450 MELAKA

30

Pabs Patm

780 mbar

930 mbar

h = ?

BMCT 2123 THERMODYNAMICS ITUTORIAL 01

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13. Both a gage and a manometer are attached to a gas tank to measure its pressure. If thereading on the pressure gage is 80 kPa, determine the distance between the two fluidlevels of the manometer if the fluid is:a) Mercury (= 13600 kg/m3)b) Water (= 1000 kg/m3)

14. A manometer containing oil ( = 850 kg/m3) is attached to a tank filled with air. If theoil-level difference between the two columns is 45 cm and the atmospheric pressure is 98kPa, determine the absolute pressure of the air in the tank.

15. The lower half of a 10 m-high is filled with water ( = 1000 kg/m3) and the upper halfwith oil that has a specific gravity of 0.85. Determine the pressure difference betweenthe top and bottom of the cylinder.

16. A glass tube is attached to a water pipe as shown. If the water pressure at the bottom ofthe tube is 115 kPa and the local atmospheric pressure is 92 kPa, determine how highthe water will rise in the tube, in meter. Assume g=9.8 m/s2 at that location and take thedensity of water to be 1000 kg/m3.

17. Consider a system whose temperature is 18oC. Express this temperature in R, K, and oF.

18. The boiling temperature of water decreases by about 3oC for each 1000 m rise inaltitude. What is the decrease in the boiling temperature for each 1000 m rise in altitudeina) Kelvinb) o Fahrenheitc) Rankine

80

h=?

h=10 m

Oil=850 kg/m3

Water=1000 kg/m3

Patm = 92 kPa

water

h=?

BMCT 2123 THERMODYNAMICS ITUTORIAL 01

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19. A gas is contained in a vertical, frictionless piston-cylinder device. The piston has a massof 4 kg and cross-sectional area of 35 cm2. A compressed spring above the piston exertsa force of 60 N on the piston. If the atmospheric pressure is 95 kPa, determine thepressure inside the cylinder. Assume the gravitational constant, g=9.807 m/s2.

20. A vertical, frictionless piston-cylinder device contains a gas at 500 kPa. The atmosphericpressure outside is 100 kPa, and the piston area is 30 cm2. Determine the mass of thepiston. Assume the gravitational constant, g=9.807 m/s2.

A = 35 cm2

P = ?

mp = 4 kg60 N

Patm = 95 kPa

A = 30 cm2

P = 500 kPa

mp = ?

Patm = 100 kPa