WeSolve+ reads the whole document and writes the questions for you
Upload your PDF, photograph your notebook, or point the camera. WeSolve+ writes questions from that material, explains why each answer is right, reads the chapter back to you as a podcast, and remembers every item you missed until you own it.
The tool below is a small browser-only tool and it is not WeSolve+: paste a few lines and text rules turn them into cards on the spot. The real app, the one that uses AI, is behind the link above.
Thermodynamic rules, from your notes
This is a browser-only tool, and that is all it isIt splits the text you paste by rule, and nothing else. WeSolve+ is a different thing entirely: it reads your whole PDF with AI, writes the reasoning behind every question, speaks the chapter back to you, and remembers what you missed so it can return it. Try the real app now, free!
This tool splits the text you paste by rule and returns cards. It cannot read a diagram or compute work, so it works on the rules you already wrote down.
Temperature is an average, not a total
It measures the average kinetic energy per particle, which is why a small very hot object can carry less total energy than a large warm one. Confusing temperature with heat is the most common conceptual error in the unit, and it produces answers that are wrong in a way the marker can identify immediately.
The first law is bookkeeping and the signs are the difficulty
Energy added by heating raises internal energy; work done by the gas lowers it. Almost every lost mark here is a sign, not a concept. Writing the convention at the top of the page, in words rather than symbols, is the simplest insurance available in this unit.
Four processes, each defined by what is held fixed
Isothermal holds temperature, adiabatic exchanges no heat, isobaric holds pressure, isochoric holds volume. Each fixes one term in the first law, which is why identifying the process is the first step rather than a detail. The gas law then supplies whatever is missing.
The area under a pressure volume curve is the work
That single fact converts a graph question into an area question, and it explains why a vertical line on such a diagram does no work at all. Students who compute work from formulas when a diagram was supplied are doing more arithmetic than the question intended.
Entropy explains why some processes only run one way
Entropy of an isolated system does not decrease, which is why heat flows from hot to cold and not back without help. Questions phrase this as asking why a described process is impossible, and naming the second law with a reason is the complete answer.
What to photograph for Thermodynamics
Diagrams with your sign conventions written out. Related: Physics C Mechanics Unit 2, photo to quiz and pricing.
Sources used on this page
- College Board, AP Physics 2
- Thermodynamics
- Ideal gas law
- Entropy
- Heat engine
- Active recall
- Spaced repetition
- Testing effect
- Forgetting curve
- Generation effect
- Judgment of learning
- Metacognition
- Desirable difficulty
- Distributed practice
- Formative assessment
- Flashcard
- Cloze test
- Multiple choice
- Test (assessment)
- Educational assessment
- Advanced Placement
- Curriculum
- Study skills
- Study guide
- Note-taking
- Overlearning
- Instructional scaffolding
- Item analysis
- Mastery learning
| Process | Held constant | Consequence |
|---|---|---|
| Isothermal | Temperature | Internal energy unchanged |
| Adiabatic | No heat exchanged | Energy change is all work |
| Isobaric | Pressure | Work is pressure times volume change |
| Isochoric | Volume | No work is done |
| Any process | Nothing | Use the area under the curve |
| Cycle | Returns to start | Internal energy change is zero |
What is AP Physics 2 Unit 9?
Thermodynamics: the microscopic picture of gas particles, the ideal gas law, the first and second laws, and pressure volume diagrams.
What is the difference between temperature and heat?
Temperature is the average kinetic energy per particle. Heat is energy transferred because of a temperature difference. Confusing them is the unit's most common error.
Where are marks actually lost here?
On sign conventions in the first law. Writing the convention in words at the top of the page prevents most of them.
How do I identify the process?
By what is held constant: temperature, pressure, volume, or no heat exchange. Each fixes one term in the first law, so identification comes first.
What does the area under a pressure volume curve mean?
The work done. That turns a graph question into an area question and explains why a vertical line does no work.
Why can heat not flow from cold to hot on its own?
Because entropy of an isolated system does not decrease. Naming the second law with that reason is a complete answer.
Last updated: 2026-08-15