AQA GCSE Combined Science: Trilogy Physics Paper 2 (Foundation), 2022: Question 7

12 marks · Standard Demand difficulty · Short Answer

Calculate work done, force, and speed in the context of a wheelchair marathon race and explain factors affecting speed.

Practise this question

Question

The image shows a wheelchair race at the London Marathon with a distance of 42,000 m. It contains five sub-questions: 07.1 asks for the equation linking distance, force, and work done; 07.2 asks to calculate average air resistance given 3,360,000 J of work; 07.3 is a multiple-choice question for the speed equation; 07.4 asks to calculate average speed given a time of 5,600 seconds; 07.5 asks for an explanation of why speed changes during the race.
Question text

07 Figure 10 shows competitors in the wheelchair race at the London Marathon.

The distance of the London Marathon is 42 000 m

Figure 10

Use the Physics Equations Sheet to answer questions 07.1 and 07.2.

07.1 Write down the equation that links distance (s), force (F) and work done (W).

[1 mark]

07.2 During the race competitors work against air resistance.

The work done against air resistance by the winner of the race was 3 360 000 J

Calculate the average air resistance acting on the winner of the race.

[3 marks]

Average air resistance = N

Use the Physics Equations Sheet to answer questions 07.3 and 07.4.

*0227.*3 Which equation links distance travelled, speed and time?

[1 mark]

Tick ( ) one box.

distance travelled = speed × time

time = distance travelled × speed

speed = distance travelled × time

07.4 The distance of the London Marathon is 42 000 m

The winning time for the race was 5600 seconds.

Calculate the average speed of the winner of the race.

[3 marks]

Average speed =25 m/s

07.5 Explain why the speed of a competitor changes during the race.

[4 marks]

Mark scheme

Show the mark scheme The mark scheme lists the following: 07.1 requires 'work done = force x distance'; 07.2 shows the calculation 3,360,000 / 42,000 = 80 N; 07.3 identifies 'distance travelled = speed x time'; 07.4 shows the calculation 42,000 / 5,600 = 7.5 m/s; 07.5 uses a level-based marking system for explaining speed changes due to factors like terrain, fatigue, and race tactics.

Question 7

AO /

Question Answers Extra information Mark

Spec. Ref.

07.1 work done = force × distance 1 AO1

(along the line of action of the 6.5.2

force)

or

W = F s

AO /

Spec. Ref.

07.2 3 360 000 = F × 42 000 1 AO2

6.5.2

3 360 000 1

F =

42 000

F = 80 (N) 1

AO /

Spec. Ref.

07.3 distance travelled = speed × 1 AO1

time 6.5.4.1.5

AO /

Spec. Ref.

07.4 42 000 = v × 5600 1 AO2

6.5.4.1.2

42 000 1

v =

5600

v = 7.5 (m/s) 1

AO /

Question Answers Mark

Spec. Ref.

07.5 Level 2: Relevant points (reasons/causes) are identified, given in 3–4 AO3

detail and logically linked to form a clear account. 6.5.4.1.2

Level 1: Relevant points (reasons/causes) are identified, and there 1–2

are attempts at logical linking. The resulting account is not fully

clear.

No relevant content 0

Indicative content

the effect on speed must be consistent with the cause of the

change

• competitors accelerate at the start

• so speed increases

• the road is not flat

• so speed increases going downhill and / or speed decreases

going uphill

• the competitor goes round a bend

• so speed decreases

• competitors may tire towards the end (so the force they exert

decreases)

• so they slow down

• competitors may sprint during the race

• causing speed to increase

• may get a puncture

• so speed would decrease or they would stop

• resistive forces on competitors may increase/decrease

• so speed would decrease/increase

Total Question 7 12

How to answer it

Forces, Work, and Motion in a Marathon

What this question tests

This question assesses your ability to recall and apply physics equations for Work Done and Average Speed. It also tests your understanding of how forces (like air resistance and gravity) and human factors (like fatigue) cause changes in motion during a real-world event.

Part 07.1 & 07.2

Work Done and Air Resistance

Calculating force from energy and distance

💡 Key Knowledge

  • Work Done is the energy transferred when a force moves an object through a distance.
  • Equation: W = F s
  • Units: Work ( J ), Force ( N ), Distance ( m ).

✅ Correct Answers

07.1: work done = force × distance

07.2: 80 N

📐 Calculation Steps (07.2)

  1. Identify the values: Work (W) = 3,360,000 J; Distance (s) = 42,000 m.
  2. Substitute into the equation: 3,360,000 = F × 42,000
  3. Rearrange to find Force: F = 3,360,000 / 42,000
  4. Final Answer: 80 N

❌ Common Errors

  • Unit Confusion: Students sometimes try to convert 42,000 m into km. In this equation, distance must be in metres.
  • Rearranging: Ensure you divide the Work by the Distance, not the other way around.
Part 07.3 & 07.4

Calculating Average Speed

Using the distance-speed-time relationship

🧠 Exam Technique

When asked to "tick one box," always double-check the units. Speed is distance divided by time, so the only equation that fits is the one where distance is the product of speed and time.

✅ Correct Answers

07.3: distance travelled = speed × time

07.4: 7.5 m/s

📐 Calculation Steps (07.4)

  1. Identify values: Distance = 42,000 m; Time = 5,600 s.
  2. Substitute: 42,000 = v × 5,600
  3. Rearrange: v = 42,000 / 5,600
  4. Final Answer: 7.5 m/s
Part 07.5

Explaining Changes in Speed

Linking causes to effects

💡 Key Knowledge

Speed changes when there is a resultant force. If the forward force (from the athlete) is greater than the resistive forces (air resistance/friction), they accelerate. If resistive forces are greater, they decelerate.

🧠 How to get 4 Marks (Level 2)

To reach the top marks, you must provide linked points. Don't just list things that happen; explain how they affect the speed.

  • The Start: Competitors accelerate at the start, so speed increases.
  • Terrain: The road isn't flat; speed increases going downhill and decreases going uphill.
  • Bends: Taking a corner usually requires slowing down to maintain control.
  • Fatigue: Competitors tire towards the end, exerting less force, so speed decreases.
  • Resistive Forces: Changes in wind (air resistance) can increase or decrease speed.

❌ Examiner Insight: Common Pitfalls

Many students lose marks here by being too vague. Writing "they might get tired" only identifies a reason. To get the mark, you must link it: "...so the force they exert decreases, causing them to slow down."

Topics

Physics

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.