AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Students should be able to describe the energy transfer involved when work…
Full specification wording
Work done and energy transfer: Students should be able to describe the energy transfer involved when work is done.
When a force moves an object through a distance, work is done and energy is transferred from one store to another.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 11 of 13
- 2 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
When a force moves an object through a distance, work is done and energy is transferred from one store to another. The work done equals the energy transferred, calculated as force × distance moved along the force direction, W = F s. For example, lifting a 20 N weight 1.5 m transfers 30 J from the chemical store of your muscles to the gravitational potential store of the weight. Friction does negative work, transferring energy from kinetic to thermal stores. Describe the transfer by naming the initial store, the mechanism (the force doing work), and the final store, then state that the energy transferred equals the work done.
What earns the marks
- Work is done when a force causes an object to move through a distance in the direction of the force.
- The energy transferred is equal to the work done, so W = F s where F is the force in newtons and s is the distance in metres.
- A complete description names the store energy leaves, the force doing the work, and the store energy enters.
- For a lifted object, chemical energy in muscles is transferred to the gravitational potential store of the object.
- For a sliding object, kinetic energy is transferred to the thermal store of the surroundings by friction.
- If the force and motion are perpendicular, no work is done and no energy is transferred by that force.
Common mistakes and how to put them right
Thinking that holding a heavy object still involves work.
Put it right: No distance is moved, so no work is done and no energy is transferred by the supporting force.
Using the total distance travelled rather than the distance moved along the line of the force.
Put it right: Only the component of displacement parallel to the force contributes to work done.
Forgetting to name the energy stores in a description.
Put it right: Examiners expect stores (for example chemical, gravitational potential, kinetic, thermal) rather than vague terms such as 'energy is used up'.
Exam tips
- Use the structure 'energy is transferred from the ... store to the ... store by the force doing work' to make your description complete.
- Check that the distance is in metres and the force in newtons before calculating; convert cm to m by dividing by 100.
- If a question asks you to describe rather than calculate, still quote W = F s to show the link between work done and energy transferred.
Try the lesson
The start of the Work done and energy transfer: Students should be able to describe the energy transfer involved when work is done. lesson, made from checked teaching notes for this specification point.
Have a go first
A pupil pushes a box across a desk. The pupil does work on the box. Which energy transfer describes what happens to the energy transferred by the pupil's push?
Listen
When a force moves an object through a distance, work is done and energy is transferred from one store to another. The work done equals the energy transferred, calculated as force × distance moved along the force direction, W = F s. For example, lifting a 20 N weight 1.5 m transfers 30 J from the chemical store of your muscles to the gravitational potential store of the weight. Friction does negative work, transferring energy from kinetic to thermal stores. Describe the transfer by naming the initial store, the mechanism (the force doing work), and the final store, then state that the energy transferred equals the work done. A strong answer earns marks for these points. Work is done when a force causes an object to move through a distance in the direction of the force. The energy transferred is equal to the work done, so W = F s where F is the force in newtons and s is the distance in metres. A complete description names the store energy leaves, the force doing the work, and the store energy enters. For a lifted object, chemical energy in muscles is transferred to the gravitational potential store of the object. Exam tip: Use the structure 'energy is transferred from the ... store to the ... store by the force doing work' to make your description complete.
Key words
Say what each word means before you turn the card.
Work done
Try answering aloud or in your head before turning the card.
Energy transfer
Try answering aloud or in your head before turning the card.
See every definition
- Work done
- Occurs when a force causes an object to move through a distance in the direction of the force.
- Energy transfer
- Movement of energy from one store to another, described by naming the initial store, the force doing work, and the final store.
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