Phy 1

• Power


  The rate at which energy is transferred
• Power rating


  The amount of energy an appliance transfers per second
• Higher power rating


  More energy transferred per second
• Higher power


  Less time needed to heat food to the same temperature
• Watts (W)


  Unit of power
• Kilowatts (kW)


  1 kilowatt = 1000 watts
• Converting kW to W

  Multiply by 1000
• Converting W to kW

  Divide by 1000
• Higher power rating of motor


  Transfers energy at a higher rate
• Twice as powerful engine

  Reaches 60 mph in half the time
• Electrical appliances that transfer energy by heating

  • Kettle, cooker, oven, tumble dryer, hairdryer
• Electrical appliances used for things other than heating


  • TV, DVD player, radio, fridge, computer, electric drill, lawnmower
• Calculating power


  power = energy transferred / time
• The students have the following equipment available: bathroom scales, tape measure, stopwatch
• An electric kettle has a power rating of 3 kW
• Energy transferred per second by 3 kW kettle

  3 kJ or 3000 J
• An electric shower has a higher power rating than an electric kettle
• Scientific vocabulary


  • Power, Work, Joule (J), Watt (W), Second (s), Rate
• Head - write main ideas that you have learnt
• Heart - write something you have felt about the topic
• Bin - write something you didn't find interesting
• Bag - write something you want to know more about, a take away