Watt

The watt (symbol: W) is the SI derived unit of power, equal to one joule per second.

Discussion
A human being climbing a flight of stairs is doing work at the rate of about 200 watts; a trained athlete can work at up to 900 watts for short periods. An automobile engine produces work at a rate of around 100 000 watts (approximately 134 horsepower). A typical household incandescent lightbulb uses 40 to 100 watts.

Definition
One watt is one joule (the SI unit of energy) per second.


 * $$ 1 \ \mathrm{W} = 1 \ \dfrac{\mathrm{J}}{\mathrm{s}}$$ = $$1 \ \dfrac{\mathrm{kg} \cdot \mathrm{m^2}}{\mathrm{s^3}}$$ = 1 newton meter per second

Origin
The watt is named after Watt James for his contributions to the development of the steam engine, and was adopted by the Second Congress of the British Association for the Advancement of Science in 1889 and by the 11th Conférence Générale des Poids et Mesures in 1960.