GCSE Physics (AQA)

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Calculating Power

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Energy Energy changes in a system, and the ways energy is stored before and after such changes

Calculating Power

3:32 Power
Spec 4.1.1.4
Previous Power Next Principle of Conservation of Energy
  • Power depends on energy transferred or work done and the time taken.
  • Power equation: Power (P) = Energy transferred (E) / Time (T).
  • Work done is the energy transferred when a force moves an object a certain distance.
  • Power can also be expressed as: Power (P) = Work done (W) / Time (T).
  • Power is measured in watts (W), time in seconds (S), and energy in joules (J).
  • One watt is the power of a process that transfers one joule of energy in one second.
  • Example 1: Car engine does 34,000 joules of work in 8 seconds to accelerate.
  • Power calculation: Power = 34,000 J / 8 s = 4,250 W.
  • Example 2: A 2,400 W kettle takes 4 minutes to boil a liter of water.
  • Convert time: 4 minutes = 240 seconds.
  • Energy calculation: Energy transferred = Power x Time = 2,400 W x 240 s = 576,000 J.

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