AQA GCSE Combined Science: Trilogy Physics Paper 1 (Foundation), 2022: Question 2

11 marks · Standard Demand difficulty · Short Answer

Analyze energy changes, calculate gravitational and elastic potential energy, and evaluate efficiency in a lift and counterweight system.

Practise this question

Question

Figure 3 shows a lift system with a lift at the bottom of a building, connected by a cable over two pulleys to a counterweight. The diagram labels brakes, an electric motor, and the cable. The question consists of seven parts: determining the relative distance the counterweight moves, identifying the change in its gravitational potential energy, calculating the GPE change of the lift using mass 1300kg and height 4m, completing sentences about kinetic and internal energy transfers due to friction, identifying factors affecting motor energy transfer, calculating elastic potential energy of the cable with a spring constant of 880,000 N/m and extension of 0.015m, and selecting how efficiency affects energy transfer.
Question text

02 Figure 3 shows a lift near the bottom of a building.

The lift is attached by a cable to a counterweight.

An electric motor moves the lift.

The lift is moving up.

Figure 3

02.1 As the lift moves up, how far does the counterweight move down?

[1 mark]

Tick ( ) one box.

A shorter distance than the lift.

The same distance as the lift.

A longer distance than the lift. 9

02.2 What happens to the gravitational potential energy of the counterweight as it

moves down?

[1 mark]

Tick ( ) one box.

It decreases

It stays the same

*08* It increases

02.3 Calculate the change in gravitational potential energy of the lift when it

moves up 4.0 m

The mass of the lift is 1300 kg

gravitational field strength = 9.8 N/kg

Use the equation:

gravitational potential energy = mass × gravitational field strength × height

[2 marks]

Change in gravitational potential energy = J

02.4 Complete the sentences.

Choose answers from the box.

[2 marks]

chemical elastic potential gravitational potential

internal kinetic

Friction between the brakes and the cable causes the speed of the lift to decrease.

*09* As the speed decreases, there is a decrease in the

energy of the lift.

As the speed decreases, there is an increase in the

energy of the brakes.

02.5 The motor transfers different amounts of energy each time people use the lift.

Which factors affect the amount of energy transferred by the motor as the lift moves?

[2 marks]

Tick ( ) two boxes.

The distance moved by the lift

The height of the building

The length of the steel cable

The maximum power of the motor

The weight of the people in the lift 11

02.6 The weight of the lift and the counterweight stretch the cable by 0.015 m

The cable acts like a spring with a spring constant of 880 000 N/m

Calculate the elastic potential energy of the stretched cable.

Use the equation:

*10* elastic potential energy = 0.5 × spring constant × (extension)2

[2 marks]

Elastic potential energy = J

02.7 A lift system using a counterweight is more efficient than a lift system that does not

use a counterweight.

How does having a more efficient system affect the energy transferred by the motor?

[1 mark]

Tick ( ) one box.

Less energy is transferred.

The same amount of energy is transferred.

More energy is transferred.

Mark scheme

Show the mark scheme The mark scheme for question 2 provides the following answers: 02.1 - 'the same distance as the lift'; 02.2 - 'it decreases'; 02.3 - calculation showing 1300 x 9.8 x 4.0 = 50960 J; 02.4 - 'kinetic' then 'internal'; 02.5 - 'the distance moved by the lift' and 'the weight of the people in the lift'; 02.6 - calculation showing 0.5 x 880000 x 0.015 squared = 99 J; 02.7 - 'less energy is transferred'. It also lists the assessment objectives and specification references for each part, totaling 11 marks.

Question 2

AO /

Question Answers Extra information Mark

Spec. Ref.

02.1 the same distance as the lift 1 AO2

6.1.1.1

AO /

Spec. Ref.

02.2 it decreases 1 AO2

6.1.1.1

AO /

Spec. Ref.

02.3 E = 1300 × 9.8 × 4.0 1 AO2

6.1.1.2

E = 50960 (J) allow 51000 (J) 1

AO /

Spec. Ref.

02.4 this order only AO1

kinetic 1 6.1.1.1

6.3.2.1

internal 1

AO /

Spec. Ref.

02.5 the distance moved by the lift 1 AO2

6.1.1.2

the weight of the people in the 1

lift 9

AO /

Spec. Ref.

2.6 E = 0.5 × 880 000 × 0.0152 1 AO2

e

6.1.1.2

Ee = 99 (J) 1

AO /

Spec. Ref.

2.7 less energy is transferred 1 AO1

6.1.2.2

Total Question 2 11

How to answer it

Energy Transfers and Efficiency in a Lift System

What this question tests

This question assesses your understanding of energy stores (GPE, kinetic, internal, and elastic), energy transfers, and your ability to perform multi-step calculations using standard physics equations. It also tests your grasp of efficiency in a mechanical system.

Part 02.1 & 02.2

The Counterweight System

💡 Key Knowledge

  • In a pulley system, the cable length is fixed. If one side moves up, the other must move down by the same amount.
  • Gravitational Potential Energy (GPE) depends on height. If an object moves down (closer to Earth), its GPE store decreases.

✅ Correct Answers

  • 02.1: The same distance as the lift.
  • 02.2: It decreases.
Part 02.3

Calculating GPE Change

Calculate the change in gravitational potential energy of the lift.

📐 Step-by-Step Calculation

  1. Identify the values: Mass (m) = 1300 kg, g = 9.8 N/kg, Height (h) = 4.0 m.
  2. State the equation: GPE = mass × gravitational field strength × height
  3. Substitute: 1300 × 9.8 × 4.0
  4. Final Answer: 50 960 J (or 51 000 J)

🧠 Exam Technique

Always show your substitution! Even if you make a calculator error, you will gain 1 mark for showing the correct numbers in the correct places. The mark scheme allows for rounding to 2 significant figures (51 000 J), but the exact answer is safer.

Part 02.4

Energy Transfers & Friction

✅ Correct Answers

As the speed decreases, there is a decrease in the kinetic energy of the lift.

As the speed decreases, there is an increase in the internal energy of the brakes.

🧠 Examiner Commentary

Students often confuse "thermal" and "internal" energy. While "thermal" is often accepted, internal energy is the more precise term for the total kinetic and potential energy of the particles in the brakes. Note: The marks are awarded for the correct order only.

Part 02.5

Factors Affecting Energy Transfer

💡 Key Knowledge

The motor does work to move the lift. Work Done = Force × Distance. Therefore, the energy transferred depends on:

  • Force: The total weight being lifted (lift + people).
  • Distance: How far the lift travels.

✅ Correct Answers (Tick Two)

  • The distance moved by the lift.
  • The weight of the people in the lift.
Part 02.6

Elastic Potential Energy Calculation

📐 Step-by-Step Calculation

  1. Identify the values: Spring constant (k) = 880 000 N/m, Extension (e) = 0.015 m.
  2. Equation: Eₑ = 0.5 × k × e²
  3. Substitute: 0.5 × 880 000 × (0.015)²
  4. Calculate: 0.5 × 880 000 × 0.000225
  5. Final Answer: 99 J

❌ Common Errors

  • Forgetting to square: The most common mistake is forgetting to square the extension (0.015).
  • Squaring the whole line: Only the extension is squared, not the spring constant or the 0.5.
Part 02.7

Efficiency

💡 Key Knowledge

Efficiency is a measure of how much energy is transferred usefully compared to the total energy put in. A more efficient system wastes less energy as heat. This means the motor doesn't have to work as hard to achieve the same result.

✅ Correct Answer

Less energy is transferred.

Topics

Physics · P1: Energy · P3: Particle Model of Matter

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Physics Paper 1 (Foundation), 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.