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.

Work and power are often confused with each other. The difference is quite simple. Power is independent of time, whereas work is the result of power and time. Power is a snapshot, it describes what something can do, but on its own it does not lead to anything. Only when the power is achieved over a certain period of time does something come about, namely work.
The confusion not only occurs with the two quantities, but even more frequently with their units. For power, this is the watt, for work, the watt second or watt hour. People tend to simplify things and so the latter are often improperly shortened to watts, which is of course simply wrong.
You sometimes come across terms such as watt hours or watt seconds per time, where the time can be shortened out here. Nevertheless, such information is sometimes useful. For example, if a machine does 8000 watt hours of work in 10 hours, then it has a power of 800 watts, but this is then the average power and probably not the maximum power to which a power specification otherwise often refers.

Physics commonly uses SI units. Here is a calculator to convert units.