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Work Done (Oxford AQA IGCSE Combined Science Double Award)

Revision Note

Leander Oates
Oxford AQA Combined Science Double Award: PhysicsOxford AQA Physics

Work Done

  • Work is done when a force causes an object to move through a distance

    • If a force is applied but the object doesn't move then no work is done

  • When work is done energy is transferred

  • For example:

    • When work is done against frictional forces, energy is transferred by heating

    • When work is done against a gravitational field, energy is transferred mechanically

Work done to move a box

A man pushing a large object across a distance, for IGCSE & GCSE Physics revision notes
Work is done when a force is used to move an object in the same direction it is acting

  • The formula for work done is:

Work = force × distance moved in the direction of the force

W space equals space F d space

  • Where:

    • W = work done in joules (J) or newton-metres (N m)

    • F = force in newtons (N)

    • d = distance in metres (m)

Worked Example

A car moving at speed begins to apply the brakes. The brakes of the car apply a force of 500 N which brings it to a stop after 23 m.

A car moving over a distance of 23 metres. A force vector points from the car in the backward direction showing 500 N

Calculate the work done by the brakes in stopping the car. 

Answer:

Step 1: List the known quantities

  • Distance, d = 23 m

  • Force, F = 500 N

Step 2: Write out the equation relating work, force and distance

W = F × d 

Step 3: Calculate the work done on the car by the brakes

W = 500 × 23

W = 11 500 J

Worked Example

A meteorite travels at a constant speed through the vacuum of space. When it reaches Earth's atmosphere it burns up.

Describe the energy transfers taking place that cause the meteorite to burn as it enters the Earth's atmosphere.

Answer:

Step 1: Identify the initial store of energy

  • The meteorite is moving through space, therefore it has energy in its kinetic store

Step 2: Identify the energy transfer pathway

  • When the meteorite enters Earth's atmosphere, it experiences frictional forces due to air resistance, therefore energy is transferred by heating

Step 3: Describe the energy transfer

  • Energy is transferred from the kinetic store of the meteorite to the thermal store of the meteorite and the thermal store of the air particles

  • The energy transferred by heating is great enough for the meteorite to burn up

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    Leander Oates

    Author: Leander Oates

    Expertise: Physics

    Leander graduated with First-class honours in Science and Education from Sheffield Hallam University. She won the prestigious Lord Robert Winston Solomon Lipson Prize in recognition of her dedication to science and teaching excellence. After teaching and tutoring both science and maths students, Leander now brings this passion for helping young people reach their potential to her work at SME.

    Caroline Carroll

    Author: Caroline Carroll

    Expertise: Physics Subject Lead

    Caroline graduated from the University of Nottingham with a degree in Chemistry and Molecular Physics. She spent several years working as an Industrial Chemist in the automotive industry before retraining to teach. Caroline has over 12 years of experience teaching GCSE and A-level chemistry and physics. She is passionate about creating high-quality resources to help students achieve their full potential.