AQA GCSE Physics Physics Paper 1 (Higher), November 2020: Question 10

10 marks · Standard Demand difficulty · Short Answer

Describe gas particle movement, calculate new pressure when volume changes at constant temperature, and explain the effect of temperature increase on gas pressure.

Practise this question

Question

Figure 15 shows a helium-filled balloon. Question 10.1 asks to tick two boxes describing gas particle movement from six options. Question 10.2 asks to calculate the new pressure of the helium when volume decreases from 0.030 m³ to 0.025 m³ at constant temperature. Question 10.3 asks to explain why increasing the temperature of the helium at constant volume increases the pressure.
Question text

10 Figure 15 shows a balloon filled with helium gas.

Figure 15

10.1 Which statements describe the movement of the gas particles in the balloon?

[2 marks]

Tick ( ) two boxes.

The particles all move in a predictable way.

The particles move at the same speed.

The particles move in circular paths.

The particles move in random directions.

The particles move with a range of speeds.

The particles vibrate about fixed positions.33

10.2 The pressure of the helium in the balloon is 100 000 Pa.

The volume of the balloon is 0.030 m3.

The balloon is compressed at a constant temperature causing the volume to decrease

to 0.025 m3.

No helium leaves the balloon.

Calculate the new pressure in the balloon.

[4 marks]

New pressure = Pa

10.3 The temperature of the helium in the balloon was increased.

The mass and volume of helium in the balloon remained constant.

Explain why the pressure exerted by the helium inside the balloon would increase.

[4 marks]

Mark scheme

Show the mark scheme The mark scheme gives answers for questions 10.1, 10.2, and 10.3. For 10.1, it awards marks for selecting random directions and a range of speeds. For 10.2, it shows working and the final answer of 120 000 Pa using Boyle's Law. For 10.3, it outlines marking points covering kinetic energy, collision frequency, collision force, and pressure.

Question 10

AO /

Question Answers Extra information Mark

Spec. Ref.

10.1 The particles move in random 1 AO1

directions. 4.3.3.1

The particles move with a range 1

of speeds.

10.2 AO2

4.3.3.2

100 000 × 0.030 = 3000 1

p × 0.025 = 3000 allow a correct substitution using 1

an incorrectly calculated value

using pV = constant

3000 allow a correct rearrangement 1

p = using an incorrect value of the

0.025

constant

p = 120 000 (Pa) allow a correct calculation using 1

an incorrect value of the

constant

allow correct substitution into

p1V1 = p2V2 for first 2 marking

points

10.3 particles would have a higher allow particles would have a 1 AO1

(mean) kinetic energy higher (mean) speed 4.3.3.1

do not accept particles vibrate

more

(so) increased number of allow greater frequency of 1

collisions with the walls of the collisions with the walls of the

balloon per second balloon

greater forces exerted in allow greater rate of change of 1

collisions (between particles and momentum (of particles)

balloon walls)

greater force exerted on same allow description using p=F/A 1

area

Total 10

How to answer it

Particle Model of Matter: Gases in Balloons

What this question tests: This question assesses your knowledge of the particle model of matter (specifically gas particle motion), applying the Boyle's Law equation ( p × V = constant ), and explaining gas pressure changes using kinetic theory in terms of particle speed, collision frequency, and force.
Question Part 10.1

Describing Gas Particle Movement

✅ Correct Answers [2 Marks]

  • The particles move in random directions. (1 mark)
  • The particles move with a range of speeds. (1 mark)

💡 Key Knowledge

Gas particles in a container are in constant, random motion. Because they undergo frequent collisions with each other and the container walls, individual particles travel at different speeds, creating a wide range of speeds at any given temperature.

🧠 Exam Technique

Read all options carefully. Watch out for distractors like "predictable way" or "same speed" which apply to solids or idealized mechanics rather than real kinetic theory.

Question Part 10.2

Calculating Pressure Change ( p × V = constant )

📐 Step-by-Step Calculation

  1. Identify the constant: Find initial pressure × initial volume.
    100 000 Pa × 0.030 m³ = 3000
  2. Set up the equation for the new state:
    p × 0.025 = 3000
  3. Rearrange to solve for new pressure (p):
    p = 3000 / 0.025
  4. Calculate final answer with units:
    p = 120 000 Pa

❌ Common Errors & Traps

  • Forgetting constant product: Students sometimes divide pressure by volume instead of recognizing that p₁V₁ = p₂V₂ .
  • Rearranging incorrectly: Ensure you divide the constant by the *new* volume, not the old one.
Mark Breakdown: 4 marks total. 1 mark for calculating constant (3000), 1 mark for correct substitution, 1 mark for correct rearrangement, 1 mark for final answer of 120 000 Pa.
Question Part 10.3

Explaining Pressure Increase Due to Temperature

✅ Marking Points Required [4 Marks max]

  • Point 1: Particles have a higher (mean) kinetic energy / higher (mean) speed.
  • Point 2: Increased number/frequency of collisions with the walls of the balloon per second.
  • Point 3: Greater forces exerted during collisions (greater rate of change of momentum).
  • Point 4: Greater force exerted overall on the same surface area ( p = F / A ).

🧠 Exam Technique & Top-Level Responses

To score full marks, you must follow a logical causal chain: Temperature ➔ Speed/Kinetic Energy ➔ Collisions (Frequency & Force) ➔ Pressure. Do not use vague terms like "particles vibrate more" (vibration applies to solids, not free-moving gases).

Examiner Insight: This is a classic 4-mark explanation question. Students frequently lose marks by missing either the frequency of collisions or the force of individual collisions, stopping at just "they move faster." Make sure to mention *both* aspects of the impacts against the walls!

Topics

Physics · P3: Particle Model of Matter

Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 1 (Higher), November 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.