AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
The work done by a force on an object can be calculated using the…
Full specification wording
Work done and energy transfer: The work done by a force on an object can be calculated using the equation: work done = force × distance moved along the line of action of the force W = F s work done, W, in joules, J force, F, in newtons, N distance, s, in metres One joule of work is done when a force of one newton causes a displacement of one metre.
The equation says that the joules transferred are the newtons multiplied by the metres moved along the line of action of the force.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 3 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The equation says that the joules transferred are the newtons multiplied by the metres moved along the line of action of the force. Both quantities must be in standard SI units: a force in kilonewtons or a distance in centimetres has to be converted first, and questions put one of them in the wrong unit on purpose. A 250 N push that moves a trolley 8.0 m does 250 × 8.0 = 2000 J of work. Rearranged, F = W/s and s = W/F, and mark schemes credit any correct rearrangement, so the safest route is to write the equation, substitute, then rearrange. The definition sits behind the unit: one joule is transferred when one newton moves its point of application one metre, which is why the joule and the newton-metre are the same size.
What earns the marks
- The equation work done = force × distance, or any correct rearrangement.
- Substituting values converted to newtons and metres.
- The correctly calculated work done.
- The unit J, or N m, given with the answer.
Common mistakes and how to put them right
Leaving a force in kilonewtons or a distance in centimetres in the substitution.
Multiplying by the whole journey length when part of it is at right angles to the force.
Rearranging the equation to work done = force divided by distance.
Quoting the answer in newtons because the force was the larger number in the question.
Exam tips
- Write the equation before substituting; the equation is itself a mark and it survives an arithmetic slip.
- Check the units before you multiply - kilonewtons and centimetres are the usual traps.
Try the lesson
The start of the Work done and energy transfer: The work done by a force on an object can be calculated using the equation: work done = force × distance moved along the line of action of the force W = F s work done, W, in joules, J force, F, in newtons, N distance, s, in metres One joule of work is done when a force of one newton causes a displacement of one metre. lesson, made from checked teaching notes for this specification point.
Have a go first
A force of 20 N pushes a box 3 m along the line of action of the force. Using W = F s, what is the work done on the box?
Listen
The equation says that the joules transferred are the newtons multiplied by the metres moved along the line of action of the force. Both quantities must be in standard SI units: a force in kilonewtons or a distance in centimetres has to be converted first, and questions put one of them in the wrong unit on purpose. A 250 N push that moves a trolley 8.0 m does 250 × 8.0 = 2000 J of work. Rearranged, F = W/s and s = W/F, and mark schemes credit any correct rearrangement, so the safest route is to write the equation, substitute, then rearrange. The definition sits behind the unit: one joule is transferred when one newton moves its point of application one metre, which is why the joule and the newton-metre are the same size. A strong answer earns marks for these points. the equation work done = force × distance, or any correct rearrangement. substituting values converted to newtons and metres. the correctly calculated work done. the unit J, or N m, given with the answer. Exam tip: Write the equation before substituting; the equation is itself a mark and it survives an arithmetic slip.
See it
Key words
Say what each word means before you turn the card.
work equation
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unit conversion
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rearrangement
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joules
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See every definition
- work equation
- Work done equals force multiplied by distance moved along the line of action of the force, written W = F s.
- unit conversion
- A force in kilonewtons or a distance in centimetres has to be converted to newtons and metres before substituting.
- rearrangement
- The equation can be rearranged to make force or distance the subject, as F = W/s and s = W/F.
- joules
- The unit of work done, where one joule is done when a force of one newton causes a displacement of one metre.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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Test your understanding of Work done and energy transfer: The work done by a force on an object can be calculated using the equation: work done = force × distance moved along the line of action of the force W = F s work done, W, in joules, J force, F, in newtons, N distance, s, in metres One joule of work is done when a force of one newton causes a displacement of one metre.
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