Watt

Watt

The watt (symbol: W) is a unit of power. In the International System of Units it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer. The watt is named after James Watt, an 18th-century Scottish inventor.

Etymology

The watt is named after James Watt, an 18th-century Scottish inventor who is most known for his work on improving the performance of steam engines. The decision to name the unit of power after Watt was made by the British Association for the Advancement of Science in 1882.

Definition

In terms of mechanical work, one watt is the rate at which work is done when an object's velocity is held constant at one metre per second against a constant opposing force of one newton. 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).

Conversions

One watt is equivalent to:

• 1 J/s (joule per second)
• 1 kg⋅m²/s³ (kilogram meter squared per second cubed)
• 1 N⋅m/s (newton meter per second)
• 1 ft⋅lb_f/s (foot pound force per second)
• 1 cal/min (calorie per minute)
• ≈ 0.7376 ft⋅lb_f/s (foot pound force per second)
• ≈ 0.0569 British thermal unit per hour
• ≈ 0.0009485 horsepower (mechanical)
• ≈ 0.000284 ton of refrigeration

See also

• Joule
• Kilowatt hour
• Orders of magnitude (power)
• Horsepower

External links

• What is a watt? - National Physical Laboratory

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