It is how your electricity bill is worked out when they come and read your meter every three months or so.
A kilowatt hour is also called a unit

1.  Work out how much energy (in kWh) is used for each of these:
     (a)  kW appliance used for hours  kWh
     (b)  kW appliance used for hours  kWh
     (c)  kW appliance used for days  kWh
     (d)  kW appliance used for minutes  kWh

2.  Work out the power rating of these appliances 
     (a)  kWh  used for hours  kW
     (b)  kWh  used for hours  kW
     (c)  kWh  used for days  kW
     (d)  kWh  used for minutes  kW

3.  How many hours were the following appliances used for
     (a)  A  kW  appliance transferred  kWh  h
     (b)  A  kW  appliance transferred kWh  h
     (c)  A  W  appliance transferred kWh  h
     (d)  A  W  appliance transferred kWh  h

4.  A get fit fanatic is on a rowing machine.  She can produce a power output of kW.  
  (a)  How much energy will she have burnt off in hours  
  (b)  How much energy will she have burnt off in minutes 
  (c)  If she burns off kWh of energy how long was she on the rowing machine?

   Answer (a) = kWh
   Answer (b) = KWh
   Answer (c) = minutes

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