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CAIE IGCSE Physics Gas Pressure and Collisions

Practise explaining gas pressure through particle collisions and momentum change, then relate temperature or escaping particles to collision frequency and force.

Syllabus
2026–2028
Course
Physics 0625

Exam points

  • explain pressure as particles colliding with walls and exerting force per unit area
  • link faster particles to harder or more frequent collisions and greater wall force
  • explain falling pressure when particles slow down or escape until pressures equalise

2.1.2.3—Pressure and the changes in pressure question 1

[Maximum number: 4]

Fig. 4.1 shows a pressure cooker on an electric heating element. The cooker has a tight-fitting lid.

Fig. 4.1

Fig. 4.1

As the water is heated, the pressure of the gas inside the cooker increases. Explain this increase in pressure in terms of particles.

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