IB Physics HL B.3.6 Molecular pressure model Question Bank
Practise IB Physics HL B.3.6 by applying momentum transfer, Newton’s third law and molecular pressure models to wall forces.
- Syllabus
- First assessment 2025
- Course
- Physics HL
- Level
- HL
Exam points
- Derive pressure from molecular momentum changes and collision rates at container walls.
- Use Newton’s third law and P=ρv²/3 to analyse wall forces and kinetic-theory pressure changes.
B.3.6—Molecular pressure model question 1
[Maximum number: 2]
The volume of the gas in (a) is increased to 6.8×10−4 m3 at constant temperature.
Explain, in terms of molecular motion, this change in pressure.
«volume has increased and» average velocity/KE remains unchanged «so» molecules collide with the walls less frequently/longer time between collisions with the walls
«hence» rate of change of momentum at wall has decreased «and so pressure has decreased»
The idea of average must be included Decrease in number of collisions is not sufficient for MP2. Time must be included.
Marking guidance:
Accept atoms/particles.
2 max
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