AQA GCSE Physics Physics Paper 2 (Higher), June 2022: Question 3
13 marks · Standard Demand difficulty · Short Answer
Explain factors affecting stopping distance, interpret reaction time distribution data, calculate travel time, and distinguish between average speed and velocity on a curved road.
Practise this questionQuestion
Question text
03 Speed limits on roads increase safety.
03.1 The braking distance of a car increases as the speed of the car increases.
Give two other factors that increase the braking distance of a car.
[2 marks]
03.2 Explain why the driver’s reaction time affects the thinking distance of a car.
[2 marks]
03.3 Scientists have investigated how drinking alcohol affects a person’s reaction time.
Figure 5 shows the results of the investigation.
Figure 5
Which of the following conclusions can be made using Figure 5?
[2 marks]
Tick ( ) two boxes.
Every person’s reaction time increases after drinking alcohol.
Mean reaction time increases after drinking alcohol.
Some people’s reaction time is not affected by drinking alcohol.
The change in reaction time is not the same for all people after
drinking alcohol.
There is a smaller range of reaction times after drinking alcohol.12
Figure 6 shows some speed cameras on a road.
The speed cameras determine the average speed of cars on the road.
Figure 6
03.4 The speed limit on the road in Figure 6 is 20 m/s.
The cameras in Figure 6 are 1.5 km apart.
Calculate the minimum time it takes to travel 1.5 km without breaking the speed limit.
Use the Physics Equations Sheet.
[4 marks]
13 Minimum time = s
03.5 The average speed of a car between the cameras and the average velocity of the car
between the cameras are different.
Explain why.
[3 marks]
Mark scheme
Show the mark scheme
Question 3
AO /
Question Answers Extra information Mark
Spec. Ref.
03.1 any two from: 2 AO1
• wet / icy road conditions ignore weather 4.5.6.3.3
• poor condition of brakes
• poor condition of tyres
• increased mass of car allow weight for mass
• negative gradient of the road allow going downhill
AO /
Spec. Ref.
03.2 distance = speed × time 1 AO1
4.5.6.3.2
(so) longer reaction time = 1
longer distance
AO /
Spec. Ref.
03.3 mean reaction time increases 1 AO3
after drinking alcohol 4.5.6.3.3
the change in reaction time is 1
not the same for all people after
drinking alcohol
AO /
Spec. Ref.
03.4 distance = 1500 (m) 1 AO2
4.5.6.1.2
1500 = 20 × t allow a correct substitution using 1
an incorrectly / not converted
value of distance
1500 allow a correct rearrangement 1
t = using an incorrectly / not
converted value of distance 13
75 (s) allow a correctly calculated 1
value using an incorrectly / not
converted value of distance
AO /
Spec. Ref.
03.5 velocity is a vector and speed is allow velocity includes direction 1 AO3
a scalar (speed does not) 4.5.6.1.2
road is not straight allow driver may change lanes 1
therefore direction changes so 1
the velocity changes
Total Question 3 13
How to answer it
Forces, Motion & Stopping Distances
What this question tests:
This 13-mark question examines your understanding of road safety, motion graphs, and kinematic calculations:
- Identifying physical factors that alter braking distance (distinguished from thinking distance).
- Explaining the physics behind thinking distance using speed and reaction time.
- Extracting valid conclusions from a distribution graph of reaction times.
- Rearranging the constant speed equation ( s = v × t ) and converting units ( km to m ).
- Explaining the fundamental difference between speed (scalar) and velocity (vector) on a curved path.
Factors Increasing Braking Distance
Recall of mechanical and environmental factors affecting braking
✅ Correct Answers (Choose any two)
- Wet or icy road conditions (reduced friction/grip)
- Worn / poor condition of tyres (reduced tread depth)
- Worn / poor condition of brakes (reduced friction pads)
- Increased mass / weight of the car (more passengers or luggage)
- Downhill slope / negative gradient of the road
❌ Common Errors & Mark Losses
- Writing just "weather": Too vague! The mark scheme specifically states "ignore weather". Always state the physical road condition (e.g., icy, wet).
- Thinking factors: Listing alcohol, tiredness, or drugs. These affect reaction time and thinking distance, not braking distance!
- Speed: The question already says "other than speed".
Reaction Time and Thinking Distance
Explaining the cause-and-effect relationship using motion principles
💡 Key Physics
During the reaction time, the driver has not yet pressed the brake pedal. The car travels at a steady speed during this period.
thinking distance = speed × reaction time
✅ How to Score 2/2 Marks
- Mark 1: State the formula or relationship:
distance = speed × time - Mark 2: State that a longer reaction time means a longer distance traveled before brakes are applied.
Interpreting Distribution Curves (Alcohol vs Reaction Time)
Evaluating data from overlapping distribution graphs
✅ Correct Ticks
- ☑ Mean reaction time increases after drinking alcohol.
The peak of the curve shifts to the right from ~0.52 s to ~0.85 s. - ☑ The change in reaction time is not the same for all people after drinking alcohol.
The curve becomes wider and flatter, showing a broader spread in response.
🧠 Why the Other Options are Incorrect
- "Every person's reaction time increases...": The graph shows population distributions, not tracked individuals. You cannot trace individual people.
- "There is a smaller range...": Incorrect. The curve after alcohol is wider (from ~0.35 s to 1.35 s), meaning the range has increased.
Calculation: Minimum Travel Time
Applying speed = distance ÷ time with unit conversions
📐 Step-by-Step Calculation
Distance = 1.5 km = 1.5 × 1000 = 1500 m [1 Mark]
distance = speed × time
1500 = 20 × t [1 Mark]
t = 1500 ÷ 20 [1 Mark]
t = 75 s [1 Mark]
❌ Calculation Traps
Forgetting to convert km to m gives 1.5 ÷ 20 = 0.075 s . You will lose the conversion mark, although error-carried-forward (ECF) allows partial credit if you show your working clearly.
🧠 Exam Technique
Always check that speed ( m/s ) and distance ( km ) share the same base unit ( m ) before substituting into the equation.
Speed vs Velocity on a Curved Road
Explaining the distinction between scalar and vector quantities
💡 Core Concept: Scalar vs Vector
- Speed: Scalar quantity — has magnitude (size) only.
- Velocity: Vector quantity — has magnitude and direction.
✅ 3-Mark Model Response
- Mark 1: Velocity is a vector and speed is a scalar (or velocity includes direction, whereas speed does not).
- Mark 2: The road is curved / not straight (or the car constantly changes direction / changes lanes).
- Mark 3: Because the direction of travel changes, the velocity changes (or displacement is less than distance traveled).
❌ Common Mistake
Stating only "velocity is speed in a direction" without applying it to the scenario. To gain all 3 marks, you must explicitly connect the curved road to a change in direction, which makes velocity different from speed.
Topics
Physics · P5: Forces
Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 2 (Higher), June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.