Science> Year 9> Unit 3> Checkpoint 1

Checkpoint 1

This checkpoint tests the opening block of the Energy unit: why energy matters, conservation of energy, calculations, efficiency and Sankey diagrams, and forms of energy.

SC5-EGY-01 Lessons 1-5 10 MC 3 Short Answer Checkpoint 1 of 4
CP1

Coverage

This checkpoint is cumulative. Strong performance means you can explain and justify ideas across the whole block rather than answer each lesson in isolation.

Lesson 1

Why energy matters, forms of energy (kinetic, potential, thermal, chemical, electrical, light, sound), and energy in society.

Lesson 2

The law of conservation of energy, energy transfers vs transformations, closed systems, and real-world examples.

Lesson 3

Calculating energy conservation, input equals useful output plus losses, and simple quantitative reasoning.

Lesson 4

Energy efficiency, Sankey diagrams, and why no real system is 100% efficient.

Lesson 5

Forms of energy in detail and transformations between different energy types.

Checkpoint Standard
This checkpoint expects explanation, comparison and justification. Avoid weak shortcuts like "energy is used up" or vague claims without evidence.
MC Score
0 / 10
Short Answers
3
Self-Marked
0 / 3

Common Misconceptions

Wrong "Energy is used up and disappears."
Right Energy is conserved; it transforms into other forms rather than disappearing.
Wrong "Efficiency means using less total energy."
Right Efficiency is the ratio of useful energy output to total energy input.
Wrong "A Sankey diagram shows only useful energy."
Right Sankey diagrams show both useful output and wasted energy with proportional arrows.
Wrong "All energy transformations are 100% efficient."
Right Some energy is always lost to the surroundings as waste in real systems.

Multiple Choice

UnderstandCore

1. Which statement best describes the law of conservation of energy?

AEnergy can be created in power stations
BEnergy can be destroyed when appliances are turned off
CEnergy cannot be created or destroyed, only transferred or transformed
DEnergy disappears when it becomes heat
UnderstandCore

2. A ball rolls down a hill. What energy transformation occurs?

AChemical to thermal
BKinetic to gravitational potential
CGravitational potential to kinetic
DElectrical to sound
UnderstandCore

3. What does efficiency measure?

AHow much total energy a device uses
BThe ratio of useful energy output to total energy input
CThe speed at which energy travels
DThe voltage required to run a device
UnderstandCore

4. In a Sankey diagram, what does the width of each arrow represent?

AThe temperature of the energy
BThe amount of energy in that pathway
CThe speed of energy transfer
DThe colour of the energy source
ApplyCore

5. A device has an efficiency of 25%. What does this mean?

AIt uses 25% less energy than other devices
B25% of the input energy becomes useful output
C75% of the energy is created inside the device
DThe device runs at 25 volts
UnderstandCore

6. Which form of energy is stored in a stretched spring?

AKinetic energy
BGravitational potential energy
CElastic potential energy
DThermal energy
ApplyCore

7. An electric kettle transforms electrical energy into which two main forms?

ALight and sound
BThermal and kinetic
CThermal and sound
DChemical and thermal
AnalyseReasoning

8. Why can no real machine be 100% efficient?

ABecause engineers are not skilled enough
BBecause some energy is always lost to the surroundings as waste
CBecause machines need to be switched off
DBecause energy cannot be transformed
ApplyReasoning

9. A car engine receives 800 kJ of chemical energy from fuel and produces 240 kJ of useful kinetic energy. What is the efficiency?

A20%
B30%
C50%
D70%
AnalyseExtended

10. Which statement best captures the opening block of this unit?

AEnergy disappears when used
BAll machines are 100% efficient
CEnergy is conserved, can be transformed, and efficiency measures useful output
DSankey diagrams only show wasted energy

Short Answer

Understand4 marks

Explain the difference between an energy transfer and an energy transformation, giving one example of each.

Define each term and give a clear real-world example.

Apply4 marks

Describe how a Sankey diagram can help identify where energy is wasted in a system.

Explain what the diagram shows and how the widths of arrows relate to energy amounts.

Analyse5 marks

A student claims that "energy is used up" when a phone battery goes flat. Why is this statement scientifically inaccurate?

Explain what actually happens to the energy, referring to conservation and transformations.

Model Answers

+

Multiple Choice

1: C. Energy cannot be created or destroyed, only transferred or transformed.

2: C. Gravitational potential energy transforms into kinetic energy as the ball descends.

3: B. Efficiency measures useful energy output divided by total energy input, often expressed as a percentage.

4: B. The width is proportional to the amount of energy in each pathway.

5: B. 25% of the total energy input is converted to useful energy output; the rest is wasted.

6: C. A stretched spring stores elastic potential energy due to its deformation.

7: C. Most electrical energy becomes thermal energy to heat water, with a small amount as sound.

8: B. Friction, air resistance and other factors always cause some energy to be dissipated as waste heat.

9: B. Efficiency = (240 / 800) x 100 = 30%.

10: C. The opening block establishes conservation, transformations, and efficiency as core ideas.

Short Answer 1 (4 marks)

Model answer:

  • 1 mark — Energy transfer: energy moves from one place to another without changing form.
  • 1 mark — Example: heat conducted from a stove to a pan.
  • 1 mark — Energy transformation: energy changes from one form to another.
  • 1 mark — Example: chemical energy in fuel transforming to kinetic energy in a car engine.

Short Answer 2 (4 marks)

Model answer:

  • 1 mark — A Sankey diagram uses arrows to show energy flow through a system.
  • 1 mark — The width of each arrow is proportional to the amount of energy in that pathway.
  • 1 mark — Useful output and wasted energy are shown as separate arrows.
  • 1 mark — By comparing arrow widths, you can see which pathway loses the most energy and target improvements.

Short Answer 3 (5 marks)

Model answer:

  • 1 mark — The statement is inaccurate because energy is never created or destroyed.
  • 1 mark — The law of conservation of energy states total energy in a closed system remains constant.
  • 1 mark — Chemical energy in the battery is transformed into electrical energy, then into light, sound and thermal energy.
  • 1 mark — The energy is not "used up"; it is spread out and becomes less useful.
  • 1 mark — A better description: the battery has run out of stored chemical energy that can be usefully converted.

Checkpoint Summary

Conservation

You should now state and apply the law of conservation of energy to real systems.

Efficiency

You should calculate efficiency and interpret Sankey diagrams to identify waste.

Forms

You should identify and describe transformations between different energy forms.

Bridge Forward

The next block explores energy transfer mechanisms, heat, and thermal properties.

Mark Checkpoint Complete
Save your progress once you have completed the multiple choice, attempted the short answers and self-marked your responses.
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