Power (Oxford AQA IGCSE Combined Science Double Award)

Power

• Machines, such as car engines, transfer energy from one energy store to another constantly over a period of time

• The rate of this energy transfer, or the rate of work done, is called power

• Time is an important consideration when it comes to power

• Two cars transfer the same amount of energy, or do the same amount of work to accelerate over a distance

• If one car has more power, it will transfer that energy, or do that work, in a shorter amount of time

Cars with different power ratings

• Power is defined as

Energy transferred per unit time

• Therefore, power can be calculated using the equation

• Where:

  • P = power in watts (W)

  • E = energy transferred in joules (J)

  • t = time in seconds (s)

• Energy transferred is equivalent to work done

energy transferred = work done

• Therefore, power can also be calculated using the equation

• Where:

  • P = power in watts (W)

  • W = work done in joules (J) 

  • t = time in seconds (s)