Mr. Rogers' AP Physics C: IB Physics Topics

Syllabus 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter
IB SL Thermo IB HL Thermo IB HL Waves AP Review  

Topic 9: HL Thermal Physics (SL optional)

1st Law 2nd Law Processes Heat Engines HL Equations


Essential Question: In all of human knowledge, outside of religion, what comes closest to absolute truth?

Thermodynamic Systems and Concepts

Note: Here thermodynamic systems assumes a fixed mass of an ideal gas.

  1. Explain what is meant by thermodynamic system. Example: expansion and compression of an ideal gas .

  2. Describe the concepts heat, work and internal energy.

  3. Deduce an expression for the work involved in a volume change of a gas at constant pressure.


The 1st Law of Thermodynamics

  1. State the 1st law of thermodynamics.

  2. Describe the isochoric (isovolumetric), isobaric, isothermal and adiabatic processes. (The heat transferred, the work done and internal energy change should be addressed. The ideal gas equation of state should be applied to all processes except the adiabatic.)

  3. Draw and annotate thermodynamic processes and cycles on p-V diagrams.

  4. Calculate the work done in a thermodynamic cycle from a p-V diagram.  (Hint: It's area under the curve.)

  5. Solve problems involving state changes of a gas.


Lesson 1

Essential Question:

Key Concept: The 1st law of Thermodynamics.

Purpose: Show how the first law in combination with perfect gas laws can be used to evaluate idealized processes.

Discussion questions:

  1. In all of science, what principle comes closest to absolute truth?

  2. Bob has a solar panel covering 2 square meters. He buys a lens with the same area and uses it to focus the sun's light on a smaller panel with 0.2 square meters. Will he improve the electrical output from his solar cell system using the lens. (assume solar cell efficiency remains constant with temperature.)

  3. Why is hydrogen not a true energy source?

  4. Does a ceiling fan heat or cool a room?

Heat engines and heat pumps

  1. Outline the concept of the heat engine and the heat pump.

  2. Draw and annotate schematic diagrams of a heat engine and a heat pump. 

  3. Define the term thermal efficiency of a heat engine 2 ways, mathematically and in English language.

  4. Draw and annotate the Carnot cycle on a p-V diagram.

  5. State what the Carnot Cylce represents.

  6. State Carnot’s theorem.

  7. State an expression for the efficiency of a Carnot engine in terms of the temperatures of the two reservoirs.

  8. Discuss the possibility of changing the thermal efficiency by altering the reservoir temperatures.

  9. Solve problems involving heat engines and heat pumps. 

Lesson 2

Essential Question: Could the engine in a car convert 100% of the energy in the gasoline it burns into usable work?

Key Concept: Introduce the basics required for evaluating new energy related inventions.

Discussion questions:

  1. Would a friction free engine in a car be able to convert 100% of the energy in gasoline into useful work?

  2. Will a heat pump work as well in Minnesota as in Greenville SC?


Second Law of Thermodynamics and Entropy

  1. State that heat can be completely converted to work in a single process, but that continuous conversion of heat into work requires a cyclical process and the rejection of some heat.

  2. State the Kelvin–Planck formulation of the 2nd law of thermodynamics.

  3. It is sufficient for students to acknowledge the impossibility of constructing a heat engine operating in a cycle that does not transfer energy to a cold reservoir. Teachers might like to show that if this were possible then it would imply that energy can be transferred spontaneously from a cold to a hot reservoir. This leads to the Clausius statement of the 2nd law.

  4. Analyze situations in terms of whether they are consistent with the first and/or second law.

  5. State that entropy is a system property that expresses the degree of disorder in the system.

  6. State the second law in terms of entropy changes.  A statement that the overall entropy of the universe is increasing will suffice.

  7. Discuss examples of natural processes in terms of entropy changes.

  8. Students should understand that although local entropy can decrease, any process will increase the total entropy of the system and surroundings.

  9. Discuss the idea of energy degradation in terms of the second law.

  10. Be as one with the relevant equations HL thermodynamics equations in the IB Physics Data Booklet.

Lesson 3

Essential Question: Is the universe winding down?

Key Concept: The 2nd Law of Thermo and entropy

Purpose: Introduce the basics required for evaluating new energy related inventions.

Discussion questions:

  1. Does the 2nd Law of Thermo preclude the possibility of biological evolution?



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