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The watt (symbol: W) is a derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736–1819). The unit is defined as joule per second and can be used to express the rate of energy conversion or transfer with respect to time. It has dimensions of L2MT−3. ==Examples== When an object's velocity is held constant at one meter per second against constant opposing force of one newton the rate at which work is done is 1 watt. : In terms of electromagnetism, one watt is the rate at which work is done when one ampere (A) of current flows through an electrical potential difference of one volt (V). : Two additional unit conversions for watt can be found using the above equation and Ohm's Law. : Where ohm () is the SI derived unit of electrical resistance. * A person having a mass of 100 kilograms who climbs a 3-meter-high ladder in 5 seconds is doing work at a rate of about 600 watts. Mass times acceleration due to gravity times height divided by the time it takes to lift the object to the given height gives the ''rate of doing work'' or ''power''.〔The energy in climbing the stairs is given by ''mgh''. Setting ''m'' = 100 kg, ''g'' = 9.8 m/s2 and ''h'' = 3 m gives 2940 J. Dividing this by the time taken (5 s) gives a power of 588 W.〕 * A laborer over the course of an 8-hour day can sustain an average output of about 75 watts; higher power levels can be achieved for short intervals and by athletes.〔.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「watt」の詳細全文を読む スポンサード リンク
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