Work Done and Energy Transfer
Understand Work Done and Energy Transfer for GCSE Physics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Work is done when a force moves an object, calculated using W = Fs, transferring energy between stores.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
Work is done when a force causes an object to move through a distance. Energy is transferred when work is done, and the two are numerically equal.
The equation is work done = force × distance moved along the line of action of the force. Work is measured in joules, and one joule is the work done when a force of one newton causes a displacement of one metre.
The distance must be measured along the line of action of the force. If you carry a bag horizontally, the upward force you exert does no work on the bag, because there is no movement in the direction of that force. Work done against friction transfers energy to thermal energy stores, which is why rubbing surfaces get warm.
Revision notes
The equation
Work done = force × distance moved along the line of action of the force, W = Fs.
Force in newtons, distance in metres, work in joules. One joule is the work done when a force of one newton causes a displacement of one metre.
Line of action
The distance must be measured along the line of action of the force.
Carrying a bag horizontally involves an upward force but horizontal movement, so no work is done on the bag by that force. Only movement in the direction of the force counts.
Work against friction
Work done against friction causes a rise in temperature.
Energy is transferred to the thermal energy store of the objects and the surroundings. This is why brake discs heat up and why rubbing your hands together warms them.
Key points
- Work is done when a force moves an object.
- Work done = force × distance along the line of action.
- Work is measured in joules.
- One joule is one newton moving one metre.
- Work done equals energy transferred.
- Work against friction raises temperature.
Worked examples
Example 1
A force of 50 N moves an object 8 m in the direction of the force. Calculate the work done. [2 marks]
Model answer
Work done = force × distance = 50 × 8 (1 mark) = 400 J (1 mark).
Example 2
Define one joule of work. [2 marks]
Model answer
One joule is the work done when a force of one newton (1 mark) causes a displacement of one metre along the line of action of the force (1 mark).
Example 3
Explain why the brakes of a car become hot when it slows down. [2 marks]
Model answer
Work is done against friction between the brakes and the wheels (1 mark), which transfers energy to the thermal energy store of the brakes, raising their temperature (1 mark).
Common mistakes
Using distance not along the line of action.
Only movement in the direction of the force counts as work done by it.
Saying work is a force.
Work is energy transferred, measured in joules, not newtons.
Forgetting that work done equals energy transferred.
The two are numerically equal, which is often the point of the question.
Using kilometres without converting.
Distance must be in metres.
Exam tips
- Check the distance is along the line of action of the force.
- State joules for work done.
- Link work against friction to a temperature rise.
- Remember work done and energy transferred are the same quantity.
Key terms
- Work done
- Energy transferred when a force moves an object.
- Joule
- The unit of work and energy.
- Line of action
- The direction in which the force acts.
- Friction
- A force opposing motion, transferring energy to thermal stores.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.