GCSE Combined Science (AQA)

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Kinetic Energy

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Forces Work done and energy transfer

Kinetic Energy

3:49 Work, Kinetic Energy and Gravitaitonal Potential Energy
Spec 4.1.1.1 4.1.1.2 4.5.2
Previous Work & Displacement Next Kinetic & GPE Conversions
  • Kinetic energy is the energy stored in a moving object.
  • Examples include a running hare and a falling apple, both of which gain kinetic energy through movement.
  • Kinetic energy (KE) is calculated based on an object's mass and speed, using the formula KE = 0.5 * m * v^2, where:
  • m = mass in kilograms
  • v = speed in meters per second
  • KE = kinetic energy in joules
  • Direction of movement does not affect kinetic energy, hence speed is used in the formula instead of velocity.
  • The formula for kinetic energy is provided in exams, but students need to know how to rearrange and apply it.
  • Example problem: Calculate the speed of a 0.2 kg cricket ball given 200 joules of kinetic energy.
  • Rearrange the kinetic energy formula to isolate v^2 (v^2 = 2KE/m).
  • Take the square root of both sides to solve for v.
  • Substitute values into the rearranged formula to find v = sqrt(2 * 200 / 0.2) = 44.7213 m/s.
  • Round the calculated speed to two significant figures, resulting in 45 m/s.

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