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Calculate Work, Power or Time
The power is specified in watts W, the work in joules J, watt seconds Ws (= joules) or watt hours Wh. The prefixes are m=milli (thousandths), k=kilo (thousands), M=mega (millions), G= Giga (Billions).
Example: a machine with a constant output of 3 kilowatts does 83 1/3 watt hours of work in 100 seconds.
Another example: a 2000 watt hair dryer used for three minutes, i.e. 180 seconds, consumes 360000 watt seconds (2000*180) of electrical energy, which is 100 watt hours.
Physics commonly uses SI units. Here is a calculator to convert units.