10 minutes maximum

1. Which of the following terms is used when the temperature remains constant during a change in conditions for an ideal gas?

• A. isobaric change
• B. isovolumetric change
• C. isothermal change
• D. adiabatic change

2. Which of the following best describes an isobaric and an adiabatic change?

3-5. The diagrams below labelled K - N show 4 heat engines:

3. Which diagram show a Carnot Cycle heat engine?

• A. K
• B. L
• C. M
• D. N

4. Two of the diagrams illustrate the second law of thermodynamics in Clausius form and Kelvin form, both with impossible heat engines. Which shows the Clausius form and which the Kelvin form?

5. What is the formula to calculate the work done W by a Carnot Cycle heat engine?

• A. W = Q₁
• B. W = Q₁ - Q₂
• C. W = Q₁ + Q₂
• D. W = Q₂ - Q₁

6-8: The p~V graph below shows the pressure and volume changes that take place during one cycle of a Carnot Cycle heat engine. The gas in the engine can be assumed to be a monatomic ideal gas.

6. Which section(s) of the cycle show adiabatic changes in the gas?

• A. I only
• B. II only
• C. I and III
• D. II and IV

7. What is shown by the shaded area within the loop?

• A. Heat energy transferred from the hot reservoir
• B. Heat energy transferred to the cold reservoir
• C. The work done by the engine
• D. The heat lost to the surroundings

8. In the cylinder of the heat engine, the inital pressure is p and volume V. During an adiabatic change the volume increases to 2V. What is the new pressure of the gas?

• A. ${32^3 p}$
• B. ${32^⅓ p}$
• C. $ {1\over {32^3 }}p$
• D. $ {1\over {32^⅓ }}p$

9. What is the maximum efficiency of this engine?

• A. about 80%
• B. about 20%
• C. 33%
• D. 25%

10. A different hot temperature reservoir is used which changes the efficiency to 75%. If the heat flow to the cold reservoir is 2.0 kW, what is the flow from the hot reservoir?

• A. 1.5 kW
• B. 2.7 kW
• C. 6.0 kW
• D. 8.0 kW