GCSE Physics (AQA)

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Dissipated Energy

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Energy Conservation and dissipation of energy

Dissipated Energy

3:31 Conservation of Energy
Spec 4.1.2.1 4.1.1.1
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  • Energy cannot be destroyed but can be lost in non-useful forms.
  • The principle of conservation of energy states that energy cannot be created or destroyed.
  • Energy is dissipated during transfer when it changes to a form that cannot be used or stored.
  • Example of a car: Chemical energy from fuel is mainly converted to kinetic energy for movement.
  • Other outputs in a car include heat from engine friction, drag, and sound, which are dissipated energy forms.
  • Common form of dissipated energy is heat loss to surroundings, often due to resistance like drag or friction between tires and road.
  • Even processes designed to transfer thermal energy, like boiling water, experience heat loss to surroundings.
  • The amount of dissipated energy can be determined by subtracting the useful output energy from the input energy.
  • Example with an electric drill: 900 joules input, 850 joules useful output, thus 50 joules dissipated as heat or sound.
  • Example with a helicopter: 1000 megajoules of fuel input, 350 megajoules gained as gravitational potential energy, resulting in 650 megajoules dissipated.

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