AQA GCSE Combined Science: Trilogy Physics Paper 2 (Foundation), November 2021: Question 3

10 marks · Low Demand difficulty · Short Answer

Answer questions about stopping distance, reaction times using a graph, energy transfers during braking, and calculate braking distance using a given equation.

Practise this question

Question

Question 03 starts with a multiple-choice question asking to identify two factors that affect reaction time from a list of five. Below is Figure 6, a line graph plotting mean reaction time in seconds (0.5 to 1.0) against age of driver in years (15 to 60), decreasing from 0.60 s at age 17 to a minimum of 0.55 s at age 24, then linearly increasing to 0.99 s at age 60. Sub-questions 03.2 and 03.3 require reading the age and time at this minimum. Question 03.4 asks to complete sentences on the change in kinetic energy and temperature of the brakes using 'decreases', 'stays the same', or 'increases'. Question 03.5 provides speed (12 m/s) and deceleration (3.0 m/s²) to calculate braking distance using the provided formula and select the unit from 'm', 'kg', or 's'. Question 03.6 asks for one reason why drivers must know typical stopping distances.
Question text

03 The stopping distance of a car is the sum of the thinking distance and the

braking distance.

03.1 The thinking distance is affected by the reaction time of the driver.

Which two of the following can affect the reaction time of the driver?

[2 marks]

Tick ( ) two boxes.

Damaged brakes

Taking drugs

Tiredness

Wet roads

Worn tyres 11

Scientists measured the reaction time for drivers of different ages.

Figure 6 shows the results.

Figure 6

03.2 At what age did the drivers have the lowest mean reaction time?

[1 mark]

Age = years

03.3 What was the lowest mean reaction time?

[1 mark]

Time = seconds

The braking distance of a car is the distance travelled between the driver applying the

brakes and the car stopping.

03.4 Complete the sentences.

Choose answers from the box.

Each answer may be used once, more than once or not at all.

[2 marks]

decreases stays the same increases

When the brakes are applied, the kinetic energy of the

*11* car .

The temperature of the brakes 13 .

03.5 A car is travelling at a speed of 12 m/s.

The driver applies the brakes and the car decelerates at a constant 3.0 m/s2.

Calculate the braking distance of the car.

Use the equation:

(speed)2

braking distance =

2 × deceleration

Choose the unit from the box.

[3 marks]

m kg s

Braking distance = Unit

03.6 To pass the UK driving test, people must know the typical stopping distance of a car

at certain speeds.

Suggest one reason why.

[1 mark]

Mark scheme

Show the mark scheme Mark scheme table for question 03 detailing 10 marks total: 03.1 gives 1 mark each for 'taking drugs' and 'tiredness'; 03.2 accepts '24 (years)' (1 mark); 03.3 accepts '0.55 (s)' with range 0.54 to 0.56 (1 mark); 03.4 awards 1 mark for 'decreases' and 1 mark for 'increases' in that order; 03.5 awards 1 mark for substitution (12)² / (2 × 3), 1 mark for calculating 24, and 1 mark for the unit 'm'; 03.6 awards 1 mark for driving at a safe distance behind another car or stopping safely if the car in front stops.

AO /

Question Answers Extra information Mark

Spec. Ref.

03.1 taking drugs 1 AO1

6.5.4.3.2

tiredness 1

03.2 24 (years) 1 AO3

6.5.4.3.2

03.3 0.55 (s) allow answer in range 0.54 to 1 AO3

0.56 6.5.4.3.2

03.4 decreases this order only 1 AO1

6.5.4.3.4

increases 1

(12)2

03.5 braking distance = 1 AO1

(2 × 3)

1 AO2

braking distance = 24

1 AO2

unit = m

6.5.4.1.5

03.6 so they know how far behind 1 AO3

another car they should drive 6.5.4.3.3

or

so they can stop safely if the car

in front stops

Total 10

How to answer it

Forces & Motion: Stopping Distance, Reaction Time, and Braking

📌 What this question tests

This question assesses core recall, graph interpretation, and calculation skills from the Forces topic:

  • Distinguishing factors that affect thinking distance (reaction time) versus braking distance (vehicle and road conditions).
  • Reading coordinates (minimum values) accurately from a line graph.
  • Understanding energy transfers during braking (kinetic energy converting to thermal energy).
  • Substituting values into an unfamiliar or given equation and identifying correct SI units.
  • Applying science to real-world road safety scenarios.
Question 03.1 • 2 Marks

Factors Affecting Driver Reaction Time

Tick (✓) two boxes that affect reaction time

✅ Correct Answers

  • Taking drugs [1 mark]
  • Tiredness [1 mark]

💡 Key Knowledge

Stopping Distance = Thinking Distance + Braking Distance.

  • Thinking distance depends only on the driver's reaction time and speed. Factors include tiredness, alcohol, drugs, and distractions.
  • Braking distance depends on the car and conditions (brakes, tyres, wet/icy roads, speed).

❌ Common Errors

Selecting damaged brakes, wet roads, or worn tyres. These affect the mechanical grip or deceleration of the car (braking distance), not how quickly the driver's brain processes danger and hits the pedal!

Questions 03.2 & 03.3 • 2 Marks

Interpreting the Reaction Time vs. Age Graph

Reading the lowest point on Figure 6

✅ Correct Answers

03.2 Age: 24 years [1 mark]

03.3 Time: 0.55 seconds [1 mark] (allow 0.54 to 0.56 )

🧠 Exam Technique

  • Find the minimum (lowest turning point) on the line curve.
  • Check the axis scales carefully:
    • x-axis: 5 major grid intervals = 5 years, so 1 small square = 1 year. The lowest point aligns at 24 years.
    • y-axis: 0.1 s is divided into 10 small squares, so 1 small square = 0.01 s. The lowest point sits halfway between 0.50 and 0.60 at 0.55 s.
Question 03.4 • 2 Marks

Energy Changes During Braking

Complete the sentences using: decreases / stays the same / increases

✅ Correct Answers

When the brakes are applied, the kinetic energy of the car decreases. [1 mark]

The temperature of the brakes increases. [1 mark]

Must be in this exact order to score 2 marks.

💡 Key Knowledge

When a driver brakes, friction between the brake pads and the wheels does work against the moving vehicle:

  • The car slows down, so its kinetic energy decreases.
  • Energy is transferred mechanically to the thermal energy store of the brakes, causing their temperature to increase.
Question 03.5 • 3 Marks

Calculating Braking Distance

Use the formula provided to find braking distance and choose the correct unit

📐 Step-by-Step Calculation

  1. Write down values given:
    Speed = 12 m/s
    Deceleration = 3.0 m/s²
  2. Substitute into the equation:
    braking distance = (12)² / (2 × 3.0) [1 mark]
  3. Calculate value:
    (144) / 6 = 24 [1 mark]
  4. Select the unit:
    Distance is measured in metres: m [1 mark]

Final Answer: 24 Unit: m

❌ Common Errors & Traps

  • Forgetting to square: Writing 12 / 6 = 2 instead of squaring 12 first ( 12² = 144 ).
  • Order of operations: Typing 144 ÷ 2 × 3 into a calculator without brackets gives 216. Make sure the entire denominator (2 × 3 = 6) divides 144.
  • Wrong unit: Selecting kg (mass) or s (time) instead of m (distance).
Question 03.6 • 1 Mark

Application to Road Safety

Suggest one reason why drivers must know typical stopping distances

✅ Acceptable Answers (Any 1)

  • So they know how far behind another car they should drive / keep a safe following distance. [1 mark]
  • So they can stop safely if the car in front stops suddenly. [1 mark]
  • To prevent/avoid collisions and accidents when braking. [1 mark]

🧠 Exam Technique

Keep your answer focused on separation gap or avoiding a crash. Vague answers like "to drive safely" or "so they don't break the law" will not score marks. Explain how knowing the distance helps the driver make safe decisions.

Topics

Physics · P5: Forces · P1: Energy

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Physics Paper 2 (Foundation), November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.