AQA GCSE Combined Science: Trilogy Physics Paper 1 (Higher), June 2025: Question 6

10 marks · Standard Demand difficulty · Short Answer

Calculate the mass of a storage cube using its dimensions and density, and explain factors affecting the energy storage system's efficiency and power.

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Question

Question text

06 A system is designed to store excess energy from the National Grid.

• Excess energy from the National Grid powers a motor that lifts a large cube.

• To transfer the energy back to the National Grid, the cube is allowed to fall.

• The falling cube turns a generator which produces electricity.

Figure 6 shows the cube before it is lifted and after it is lifted.

Figure 6

06.1 The cube has a density of 4200 kg/m3.

Determine the mass of the cube.

Use the Physics Equations Sheet.

[4 marks]

Mass = kg

06.2 Explain why the cube is made from a material with a high density.

[2 marks]

06.3 The system is designed to store excess energy from the National Grid.

Explain how the efficiency of the system could be determined.

[2 marks]

06.4 The system in Figure 6 on page 20 needs to be able to store excess energy as

quickly as possible.

Explain one change to this system that would allow the same amount of energy to be

stored more quickly.

Do not refer to efficiency in your answer.

[2 marks]

Mark scheme

Show the mark scheme

Question 6

AO /

Question Answers Extra information Mark

Spec. Ref.

V (= 5 × 5 × 5) = 125 (m3) 1

do not allow subsequent marks

unless volume is used

06.1 AO2

subsequent marks may be 6.3.1.1

awarded if volume is incorrectly

calculated

m 1

4200 =

m = 4200 × 125 1

m = 525 000 (kg) 1

AO /

Spec. Ref.

06.2 (the greater the density) the 1 AO1

greater the mass (for a given

volume)

(so) a greater amount of energy 1 AO3

can be stored

OR 6.1.1.2

(the greater the density) the

smaller the volume (for a given

mass) (1)

(so) the same amount of energy

can be stored (for a smaller

volume) (1) – – 8464/P/1H –

AO /

Question Answers Mark

Spec. Ref.

06.3 measure the energy input from allow measure the energy input 1 AO3

the National Grid and measure to the motor and measure the

the energy output to the energy output from the

National Grid generator

(then) use the equation: MP2 dependent on MP1 1 AO1

energy output

efficiency =

energy input

18 6.1.2.2

if no other mark awarded, allow 1 mark for:

energy released when lowering the block

efficiency =

energy stored when raising block

AO /

Spec. Ref.

06.4 use a motor with a greater allow increase the power of the 1 AO1

power motor 6.1.1.4

(so) the cube / weight / mass is MP2 dependent on MP1 1

lifted more quickly

Total Question 6 10

How to answer it

Grid Energy Storage Using a Heavy Cube

Summary Checklist

What this question tests:

Calculating geometric volume of a cube and applying the density equation ( ρ = m / V ).
Understanding gravitational potential energy storage ( Eₚ = m g h ) in relation to mass and density.
Describing experimental measurements needed to calculate energy efficiency ( efficiency = output / input ).
Applying the physics concept of power ( P = E / t ) to energy transfer rates.

Question 06.1

Determining the Mass of the Cube [4 Marks]

📐 Step-by-Step Calculation

1 Calculate the volume of the cube:
From Figure 6, side length = 5 m.
Volume = 5 × 5 × 5 = 125 m³ [1 mark]

2 Select and substitute into density equation:
density = mass / volume
4200 = m / 125 [1 mark]

3 Rearrange to solve for mass (m):
m = 4200 × 125 [1 mark]

4 Final calculated value:
Mass = 525 000 kg (or 5.25 × 10⁵ kg ) [1 mark]

❌ Common Errors & Pitfalls

Confusing height with cube dimensions: Using the 25 m lift height instead of 5 m to find volume gives an immediate penalty.
Squaring instead of cubing: Calculating surface area ( 5 × 5 = 25 ) rather than 3D volume ( 5 × 5 × 5 = 125 ).
Division blunder: Dividing density by volume ( 4200 / 125 ) instead of multiplying. Remember: mass = density × volume .

Examiner Rule: Subsequent calculation marks cannot be awarded unless a volume calculation was attempted.

Question 06.2

Why Use a High-Density Material? [2 Marks]

✅ Model Answers (Choose Either Route)

Route A (Maximising Energy):

A higher density gives a greater mass for a given / fixed volume [1 mark]
Therefore, a greater amount of (gravitational potential) energy can be stored [1 mark]

Route B (Saving Space):

A higher density requires a smaller volume for a given mass [1 mark]
Therefore, the same energy can be stored in a much smaller physical space [1 mark]

🧠 Exam Technique & Physics Link

Always connect the two physics equations in your explanation:

Density = Mass / Volume & Eₚ = m × g × h

Notice how energy stored depends directly on mass ( m ). To store maximum energy without building an enormous structure, you need high mass packed into a compact size.

Question 06.3

Determining System Efficiency [2 Marks]

✅ Marking Points

Mark 1: Measure the total energy input (from the National Grid to the motor) AND measure the useful energy output (from the generator back to the National Grid).
Mark 2: Calculate efficiency using the formula:
efficiency = useful energy output / total energy input

Note: Mark 2 is dependent on identifying both input and output in Mark 1.

💡 Examiner Insight: "How It Could Be Determined"

When asked how a value can be determined, you must state:
1. What quantities you physically measure.
2. How you calculate the answer using a standard formula.
Writing only the formula without explaining what to measure restricts you to 1 mark maximum.

Question 06.4

Storing the Same Energy More Quickly [2 Marks]

✅ Model Answer

Change: Use a motor with greater power (or increase the power rating of the motor) [1 mark]
Explanation: So that the cube is lifted more quickly (faster) [1 mark]

Note: The second mark depends on correctly identifying a higher-power motor.

❌ Key Restrictions to Avoid

"Do not refer to efficiency": Stating "make the motor more efficient" scores 0 marks because the prompt explicitly forbade mentioning efficiency.
Changing the cube: Increasing the mass or height changes the amount of energy stored, but the question asks how to store the same amount faster.
Power definition: Remember that Power = Energy / Time . If Energy is fixed and Time must decrease, Power must increase!

Topics

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

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Physics Paper 1 (Higher), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.