AQA GCSE Combined Science: Trilogy Physics Paper 2 (Foundation), 2022: Question 5
14 marks · Standard Demand difficulty · Short Answer
Analyze factors affecting thinking distance, interpret a thinking distance-speed graph, and calculate final velocity using equations of motion.
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Question text
05 The stopping distance of a car is the sum of the thinking distance and the
braking distance.
05.1 Which factors affect the thinking distance?
[2 marks]
Tick ( ) two boxes.
Condition of the tyres
Driving on wet roads
Mass of the car
Tiredness of the driver
Using a mobile phone
05.2 Explain why a person should not drink alcohol and then drive.
[3 marks]
The Highway Code gives information on how thinking distance depends on the speed
of a car.
Figure 7 shows the information as a graph.
Figure 7
05.3 What is the speed of a car if the thinking distance is 16 m?
[1 mark]
Speed of car = m/s
05.4 Describe the relationship between speed and thinking distance.
[2 marks]
05.5 The Highway Code assumes the driver’s reaction time is 0.70 seconds.
Draw a line on Figure 7 to show the relationship for a driver with a reaction time
of 1.4 seconds.
[2 marks]
05.6 A car accelerates at 5.0 m/s2 over a distance of 45 m
initial velocity of the car = 0 m/s
Calculate the final velocity of the car.
Use the Physics Equations Sheet.
Give your answer to 2 significant figures.
[4 marks]
Final velocity (2 significant figures) = m/s
Mark scheme
Show the mark scheme
Question 5
AO /
Question Answers Extra information Mark
Spec. Ref.
05.1 tiredness of the driver 1 AO1
6.5.4.3.2
using a mobile phone 1
AO /
Spec. Ref.
05.2 increases reaction time 1 AO1
so increases the thinking 1 AO1
distance
so more likely to have a collision allow travels a greater distance 1 AO3
before stopping (in an
emergency) 6.5.4.3.2
AO /
Spec. Ref.
05.3 23 m/s 1 AO2
6.5.4.3.2
AO /
Spec. Ref.
05.4 directly proportional 2 AO3
allow 1 mark for as speed 6.5.4.3.2
increases thinking distance
increases
16 AO /
Spec. Ref.
05.5 straight line from the origin with 1 AO2
a greater gradient 6.5.4.3.2
through (15,21) allow a line that passes within 1
half a small square of (15,21)
dependent on MP1
AO /
Spec. Ref.
05.6 v2 – 02 = 2 × 5.0 × 45 1 AO2
6.5.4.1.5
v2 = 450 or v = √450 1
v = 21.21320343 1
v = 21 (m/s) allow a correctly rounded value 1
of v calculated using the correct
equation
Total Question 5 14
How to answer it
Stopping Distances and Equations of Motion
This question assesses your understanding of stopping distances (thinking vs braking), factors affecting reaction time, interpreting linear graphs, and applying the constant acceleration equation to calculate velocity.
Factors Affecting Thinking Distance
💡 Key Knowledge
- Thinking Distance: The distance traveled while the driver reacts. It is affected by speed and reaction time.
- Braking Distance: The distance traveled while the brakes are applied. It is affected by road conditions, tyres, and mass.
✅ Correct Answers
05.1: Tiredness of the driver AND Using a mobile phone.
05.2: Alcohol increases reaction time (1), which increases thinking distance (1), making a collision more likely (1).
🧠 Exam Technique: The "Chain of Reasoning"
In 05.2, you must link the cause to the effect. Don't just say "it's dangerous."
1. Effect on brain (longer reaction time) → 2. Effect on physics (longer distance) → 3. Outcome (crash).
❌ Common Error: "Slower Reactions"
Avoid saying "alcohol slows down reactions." While technically true, examiners want you to say reaction time increases. If time increases, you travel further before hitting the brakes.
Graph Skills: Speed vs Thinking Distance
✅ Correct Answers
- 05.3: 23 m/s (Read 16m on the y-axis, go across and down).
- 05.4: Directly proportional.
- 05.5: A straight line starting at (0,0) with a steeper gradient, passing through the point (15, 21).
🧠 Graph Drawing (05.5)
The original reaction time was 0.7s. The new time is 1.4s (exactly double). This means at any speed, the distance will be double the original line.
Example: At 15 m/s, the original distance was 10.5m. For the new line, at 15 m/s, the distance must be 21m.
Calculation: Final Velocity
Using v² - u² = 2as
📐 Step-by-Step Calculation
- Identify the variables:
Initial velocity (u) = 0 m/s
Acceleration (a) = 5.0 m/s²
Distance (s) = 45 m - Substitute into the formula:
v² - 0² = 2 × 5.0 × 45 - Simplify:
v² = 450 - Square root both sides:
v = √450 = 21.2132... - Round to 2 Significant Figures:
Final Velocity = 21 m/s
❌ The "Square Root" Trap
The most common way to lose 2 marks here is forgetting to square root the final answer. If your answer is 450 m/s for a car, ask yourself: "Is that realistic?" (450 m/s is faster than the speed of sound!)
🧠 Significant Figures
The question explicitly asks for 2 significant figures.
21.213... becomes 21.
Even if your calculation is perfect, you lose the final mark if you write 21.2 or 21.21.
Topics
Physics · P5: Forces
Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Physics Paper 2 (Foundation), 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.