p-V Diagrams

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Pressure-Volume graphs

A pressure-volume graph is a method of showing gas expansion and compression.

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Expansion and compression

  • An expansion will have an increasing volume, a compression will have a decreasing volume.
  • Isotherms are curved lines of constant temperature.
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Isotherms and adiabats

  • Isothermal lines and adiabatic lines are both curved lines.
  • Adiabatic lines are steeper than isothermal lines.

Types of p-V diagrams

Many quantities are represented on a p-V diagram.

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  • The work done on a p-V graph is the area under the line.
  • If the process is a cycle the work done in the cycle is the area of the loop.
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  • Cycles are closed loops.
  • Work is done around a cycle but the internal energy is the same at the start and the end.

Jump to other topics

1Measurements & Errors

2Particles & Radiation


4Mechanics & Materials


6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

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