joule — LLMpedia

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joule is the unit of energy in the International System of Units (SI), named after James Prescott Joule, a British physicist who studied the relationship between mechanical work and heat energy with Sadi Carnot, Rudolf Clausius, and William Thomson (Lord Kelvin). The joule is used to express the amount of energy expended or work done by a force of one newton over a distance of one meter, as defined by the National Institute of Standards and Technology (NIST) and the International Committee for Weights and Measures (ICWM). This unit is widely used in various fields, including physics, engineering, and chemistry, as recognized by the American Physical Society (APS), the Institute of Electrical and Electronics Engineers (IEEE), and the Royal Society.

Definition and units

The joule is defined as the energy expended when a force of one newton is applied over a distance of one meter, as stated by the Bureau International des Poids et Mesures (BIPM) and the National Physical Laboratory (NPL). It can also be expressed in terms of other units, such as the watt-second, where one joule is equal to one watt of power expended for one second, as defined by the International Electrotechnical Commission (IEC) and the American National Standards Institute (ANSI). The joule is also related to the calorie, a unit of energy in the centimeter-gram-second system (CGS), as used by Wilhelm Wien, Max Planck, and Albert Einstein. Additionally, the joule is used in conjunction with other units, such as the kilowatt-hour (kWh), which is commonly used by utilities like Exelon, Duke Energy, and Southern California Edison to measure electricity consumption.

The joule was named after James Prescott Joule, who first described the relationship between mechanical work and heat energy in the 1840s, as published in the Philosophical Magazine and the Proceedings of the Royal Society. Joule's work built upon the earlier research of Sadi Carnot, who is considered the father of thermodynamics, and Rudolf Clausius, who introduced the concept of entropy. The joule was officially adopted as a unit of energy in 1889 by the International Committee for Weights and Measures (ICWM), with the support of William Thomson (Lord Kelvin), Heinrich Hertz, and Oliver Heaviside. The development of the joule as a unit of energy was also influenced by the work of Alessandro Volta, Michael Faraday, and James Clerk Maxwell, who made significant contributions to the understanding of electricity and magnetism.

The joule is widely used in various applications, including electricity generation and transmission, as measured by utilities like Pacific Gas and Electric (PG&E), Commonwealth Edison (ComEd), and Tennessee Valley Authority (TVA). It is also used in mechanical engineering to calculate the energy expended by machines and engines, as designed by Nikolaus August Otto, Gottlieb Daimler, and Rudolf Diesel. In chemistry, the joule is used to express the energy changes that occur during chemical reactions, as studied by Antoine Lavoisier, Joseph Priestley, and Dmitri Mendeleev. Additionally, the joule is used in biology to measure the energy expended by organisms, as researched by Louis Pasteur, Robert Koch, and Jane Goodall.

The joule can be converted to other units of energy, such as the calorie, the British thermal unit (BTU), and the kilowatt-hour (kWh), as defined by the National Institute of Standards and Technology (NIST) and the International Committee for Weights and Measures (ICWM). One joule is equal to 0.239 calories, 0.000948 British thermal units (BTU), and 0.0002778 kilowatt-hours (kWh), as used by organizations like the United States Environmental Protection Agency (EPA), the European Union (EU), and the International Energy Agency (IEA). The joule can also be converted to units of power, such as the watt, where one joule per second is equal to one watt, as defined by the International Electrotechnical Commission (IEC) and the American National Standards Institute (ANSI).

The joule is a derived unit, meaning that it can be expressed in terms of other base units, such as the meter, the kilogram, and the second, as defined by the International System of Units (SI) and the National Institute of Standards and Technology (NIST). The joule is equal to one newton-meter, which is the product of the force (one newton) and the distance (one meter), as used by engineers like Isambard Kingdom Brunel, Gustave Eiffel, and Nikola Tesla. The joule can also be expressed in terms of other derived units, such as the watt-second, where one joule is equal to one watt of power expended for one second, as defined by the International Electrotechnical Commission (IEC) and the American National Standards Institute (ANSI).

The symbol for the joule is J, which is named after James Prescott Joule, as recognized by the International Committee for Weights and Measures (ICWM) and the National Institute of Standards and Technology (NIST). The joule is often denoted in scientific notation, where it is expressed as a product of a number and a power of ten, as used by scientists like Stephen Hawking, Neil deGrasse Tyson, and Brian Greene. For example, one megajoule (MJ) is equal to 1,000,000 joules, and one gigajoule (GJ) is equal to 1,000,000,000 joules, as defined by the International System of Units (SI) and the National Institute of Standards and Technology (NIST). Category:Units of energy