Watts, residential section of south central Los Angeles. Named after C. H. Watts, a Pasadena realtor, the section became part of Los Angeles in 1926. Artist Simon Rodia's celebrated Watts Towers are there. Historically an impoverished black ghetto, Watts was the site of six days of race riots in 1965 that claimed 34 lives and caused over $200 million in property damage. Race riots again erupted in 1992 after the acquittal of white police officers who beat a black motorist; 58 people died and approximately $1 billion in property was destroyed. The African-American population has declined in recent decades while the area's Hispanic population has grown significantly. In 1990, almost 40% of Watts's residents were living below the poverty line.

Watts may refer to:

Unit of measure

• watt, the SI derived unit of power

People

Surname

• Alan Watts, a philosopher, writer, speaker, and student of comparative religions
• André Watts, a classical pianist
• Charlie Watts, a rock drummer
• Duncan J. Watts, an Australian sociologist
• Ethan Watts, American volleyball player
• Frederick Watts, the "Father of Penn State"
• George Frederic Watts, an English painter from the Victorian era
• Heather Watts, an American ballerina and dancer
• J. C. Watts, former representative from Oklahoma in the U. S. Congress
• Naomi Watts, a British actress
• Peter Watts, science fiction author and marine-mammal biologist
• Philip Watts (naval architect), a British naval architect
• Philip Watts, former Chairman of Royal Dutch Shell
• Fraser Watts, Scottish cricketer

Nickname

• Watts (producer), a Canadian hip-hop producer

Places

• Watts, Los Angeles, California
• Watts, Oklahoma
• Watts Point volcanic centre

Events

• Watts riots

Fictional characters

• The Watts families in the UK soap operas EastEnders and Coronation Street:
• Angie Watts, a character in EastEnders
• Den Watts, a character in EastEnders
• Sharon Watts, a character in EastEnders

The watt (symbol: W) is the SI derived unit of power, equal to one joule of energy per second. It measures a rate of energy use or production.

A human climbing a flight of stairs is doing work at a rate of about 200 watts. A typical automobile engine produces mechanical energy at a rate of 25,000 watts (approximately 33.5 horsepower) while cruising. A typical household incandescent light bulb uses electrical energy at a rate of 25 to 100 watts, while compact fluorescent lights typically consume 5 to 30 watts.

Definition

One watt is the rate at which work is done when an object is moving at one meter per second against a force of one newton.

$$

1~rm{W} = 1~dfrac{rm{J}}{rm{s}} = 1~dfrac{rm{kg} cdot rm{m^2}}{rm{s^3}} = 1~dfrac{rm{Ncdot m}}{rm{s}} , .

By the definition of the units of ampere and volt, work is done at a rate of one watt when one ampere flows through a potential difference of one volt.

Origin and adoption as an SI unit

The watt is named after James Watt 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 General Conference on Weights and Measures in 1960 as the unit of power incorporated in the International System of Units (or "SI").

Derived and qualified units for power distribution

Microwatt

The microwatt (symbol:μW) is equal to one millionth (10^-6) of a watt.

Milliwatt

The milliwatt (symbol:mW) is equal to one thousandth (10^-3) of a watt.

Kilowatt

The kilowatt (symbol: kW), equal to one thousand watts, is typically used to state the power output of engines and the power consumption of tools and machines. A kilowatt is approximately equivalent to 1.34 horsepower. An electric heater with one heating-element might use 1 kilowatt.

Megawatt

The megawatt (symbol: MW) is equal to one million (10⁶) watts. Many things can sustain the transfer or consumption of energy on this scale; some of these events or entities include: lightning strikes, large electric motors, naval craft (such as aircraft carriers and submarines), engineering hardware, and some scientific research equipment (such as the supercollider and large lasers). A large residential or retail building may consume several megawatts in electric power and heating energy.

The productive capacity of electrical generators operated by utility companies is often measured in MW. Modern high-powered diesel-electric railroad locomotives typically have a peak power output of 3 to 5 MW, whereas U.S. nuclear power plants have net summer capacities between about 500 and 1300 MW.

According to the Oxford English Dictionary, the earliest citing for "megawatt" is a reference in the 1900 Webster's International Dictionary of English Language. The OED also says "megawatt" appeared in a 28 November, 1847, article in Science (506:2).

Gigawatt

The gigawatt (symbol: GW) is equal to one billion (10⁹) watts. This unit is sometimes used with large power plants or power grids.

Terawatt

The terawatt (symbol: TW) is equal to one trillion (10¹²) watts. The average energy usage by humans (about 15 TW) is commonly measured in these units. The most powerful lasers from the mid 1960s to the mid 1990s produced power in terawatts, but only for nanoseconds.

Electrical and thermal

In the electric power industry, Megawatt electrical (abbreviation: MW_e or MWe) is a term that refers to electric power, while megawatt thermal (abbreviations: MW_t, MW_th, MWt, or MWth) refers to thermal power produced. Other SI prefixes are sometimes used, for example gigawatt electrical (GW_e).

For example, the Embalse nuclear power plant in Argentina uses a fission reactor to generate 2109 MW_t of heat, which creates steam to drive a turbine, which generates 648 MW_e of electricity. The difference is heat lost to the surroundings.

Confusion of watts and watt-hours

Power and energy are frequently confused in the general media. Power is the rate at which energy is used. A watt is one joule of energy per second. For example, if a 100 watt light bulb is turned on for one hour, the energy used is 100 watt-hours or 0.1 kilowatt-hour, or 360,000 joules. This same quantity of energy would light a 40 watt bulb for 2.5 hours. A power station would be rated in watts, but its annual energy sales would be in watt-hours (or kilowatt-hours or megawatt-hours). A kilowatt-hour is the amount of energy equivalent to a steady power of 1 kilowatt running for 1 hour:

(1 kW·h)(1000 W/kW)(3600 s/h) = 3,600,000 W·s = 3,600,000 J = 3.6 MJ.

See also

References

External links

• Nelson, Robert A., " The International System of Units Its History and Use in Science and Industry". Via Satellite, February 2000.