Revision Notes

2.1.5 Pressure Changes

Pressure & Temperature

  • The molecules in a gas move around randomly at high speeds, colliding with surfaces and exerting pressure upon them


kinetic-theory, IGCSE & GCSE Physics revision notesGas molecules collide with surfaces, exerting pressure


  • When the temperature of a gas is increased, the speeds of the molecules increases
  • This causes them to collide harder against surfaces, increasing the pressure
  • Increasing the temperature of a gas (whilst keeping its volume fixed) will increase the pressure



Exam Question: Pressure & Temperature

Pressure & Volume

  • When a gas is compressed, the density of the gas increases


Pressure-vs-Volume, IGCSE & GCSE Physics revision notesWhen a gas is compressed it becomes more dense, increasing the pressure


  • This means there will be more collisions against surfaces, which will also increase the pressure
  • Decreasing the volume of a gas (whilst keeping the temperature fixed) will increase the pressure


Kinetic theory worked example, IGCSE & GCSE Physics revision notesWorked example showing the effect of compressing gas on its pressure



Exam Question: Pressure & Volume

Extended Only

Boyle's Law

  • If a gas has an original pressure, P1, and volume, V1, then its final pressure and volume (P2 and V2) will be given by the relationship:
P1V1 = P2V2

Note: The above equation only works if the temperature of the gas remains constant


Pressure and volume worked example, IGCSE & GCSE Physics revision notesWorked example showing the change in pressure of gas as the result of compression

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