THERMODYNAMIC SYSTEMS
ASSESSMENT QUESTIONS
QUESTION 1. State the condition necessary for heat to flow spontaneously from body 'A' to body 'B'.
QUESTION 2. Define, and give an example of, a thermodynamic system.
QUESTION 3. Give an example of a closed thermodynamic system in which the boundaries are not fixed.
QUESTION 4. Give an example of an open thermodynamic system.
QUESTION 5. State the SI units of:
Heat
Work
Internal energy Temperature.
QUESTION 6. When the boundary of a closed system moves outwards, is work done on
(a) the system
or (b) the surroundings?
QUESTION 7. Describe an operation in which the internal energy of a system is increased at constant volume.
QUESTION 8. Convert these Celsius temperatures to the Absolute scale: - 273°C, 0°C, 100°C, 1000°C.
QUESTION 9. Convert these Absolute temperatures to degrees Celsius: 0 K, 100 K, 273 K, 1000 K.
QUESTION 10. State three forms in which a working fluid may exist.
QUESTION 11. Convert the following pressures to bar:
1000 N m-2 100 000 N m-2 2 x 106 N m-2 3000 kN m-2
QUESTION 12. State the equation used to convert a gauge pressure into an absolute pressure.
QUESTION 13. What name is given to the energy of a fluid due to the movement of its particles?
QUESTION 14. State:
(a) the combined gas equation
(b) the characteristic gas equation.
15. (a) What are the units of specific heat capacity?
(b) What is the equation which relates R, c, and cv?
QUESTION 16. A gas with a volume of 0.1 m3, pressure of 50 kN m-2 and temperature of 20°C is compressed into a volume of 0.08 m3 and its pressure becomes 70 kN m-2. If R for the gas is 0.3 kJ kg-1 K-1, calculate:
(a) the temperature of the gas when compressed
(b) the mass of gas present.
QUESTION 17. 0.2 kg of a gas requires 3.48 kJ of energy to raise its temperature from 20°C to 50°C when heated at constant volume and 4.92 Id when heated at constant pressure of 2 bar. Calculate the value of:
(a) the characteristic gas constant R
(b) the specific volume of the gas when at a pressure of 2 bar and a temperature of 50°C.