GCSE Combined Science (AQA)

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Efficiency

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Energy Conservation and dissipation of energy

Efficiency

3:42 Efficiency
Spec 4.1.2.2
Previous Calculating Efficiency Next Improving Efficiency
  • Energy transfer converts input energy to useful and wasted energy.
  • Wasted energy is energy in a form that is not wanted or usable.
  • Example: Accelerating a car involves converting chemical energy in fuel to kinetic energy in wheels.
  • Useful output: Increased car speed.
  • Other energy transfers include thermal energy due to friction and sound energy from engine noise.
  • Thermal and sound energy are considered wasted energy in this context.
  • Efficiency of energy transfer is the proportion of input energy that becomes useful output energy.
  • Higher efficiency means more useful output from a given input.
  • Example: If 60% of energy is converted to kinetic energy, efficiency is 60%.
  • Knowing efficiency is important for reducing input energy needed for the same output.
  • More efficient processes require less input energy for the desired output.
  • Example: Two cars needing different input energies for the same kinetic energy output due to differing efficiencies.
  • More efficient car requires less fuel to achieve the same kinetic energy output.

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