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O LevelPhysicsCambridgeRevision Notes1. Motion, Forces & Energy1.7 Energy, Work & PowerKinetic Energy

Kinetic Energy (Cambridge O Level Physics)

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Dan MG

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Dan MG

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Kinetic Energy

  • Energy in an object's kinetic store is defined as:

The amount of energy an object has as a result of its mass and speed

  • This means that any object in motion has energy in its kinetic energy store

Object in Motion

1-7-2-kinetic-energy-cie-igcse-23-rn

This car has mass and is not stationary, so there is energy in its kinetic store

  • Kinetic energy can be calculated using the equation:

Ek = 12 × m × v2{"language":"en","fontFamily":"Times New Roman","fontSize":"18","autoformat":true}

  • Where:
    • EK = kinetic energy in joules (J)
    • m = mass of the object in kilograms (kg)
    • v = speed of the object in metres per second (m/s)

Worked example

Calculate the kinetic energy stored in a vehicle of mass 1200 kg moving at a speed of 27 m/s.

 Answer:

Step 1: List the known quantities

  • Mass of the vehicle, m = 1200 kg
  • Speed of the vehicle, v = 27 m/s

Step 2: Write down the equation for kinetic energy

EK = ½ mv2

Step 3: Calculate the kinetic energy

EK = ½ × 1200 × (27)2

EK = 437 400 J

Step 4: Round the final answer to 2 significant figures

EK = 440 000 J

Examiner Tip

When performing calculations using the kinetic energy equation, always double-check that you have squared the speed. Forgetting to do this is the most common mistake that students make.

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    Dan MG

    Author: Dan MG

    Expertise: Physics

    Dan graduated with a First-class Masters degree in Physics at Durham University, specialising in cell membrane biophysics. After being awarded an Institute of Physics Teacher Training Scholarship, Dan taught physics in secondary schools in the North of England before moving to SME. Here, he carries on his passion for writing enjoyable physics questions and helping young people to love physics.