One kilowatt-hour represents 3600 joules, while a megawatt-hour stands for 1000000 watts/3600000 seconds - meaning it's equivalent to roughly 12 million horsepower! Here are some additional facts about the unit of power: The International System (SI) states that one joule per second equals one watt. It has an SI base unit and several derived units that are used to measure other physical quantities associated with energy or work. The unit of power is the watt, which is abbreviated by W. I Joule = 1 kg.m 2 /s 2 and it is the unit of energy in the SI system. But this unit gets cumbersome to write in every equation, so scientists have defined another unit Joule (J), which is named after the physicist James Prescott Joule. From this, we can get the unit of work as kg.m 2 /s 2. Unit of force (which is mass times acceleration) is kg.m/s 2. In the metric system, mass is measured in kilograms, length in metres, and time in seconds. The SI or metric system has only 7 base units, and all the other units are derived from these base units. To define units of power let us look into how the SI system works. Now we know that velocity = distance/time hence: Since Work = force * distance and power = work time, then power = force * distance time. We could derive another formula for power from the formula for work. Power = V * I, where V is the voltage within the circuit, and I is the current through the circuit. While studying electricity, you would find the power is defined as: Power is the rate at which energy (heat and electrical) is transferred. the time taken to complete a work gives the power of an entity. Power is the ratio of work and time, i.e.

The word “power” is also used differently by physicists. In Physics, work done is given by force applied on an object to move a distance (d), and its formula is:Įven after applying a lot of force, if an object does not move, then in the eyes of a physicist, no work is done. The word “work” has a different meaning in the world of Physics. We will look into a few concepts around power, work, and energy in this article and discuss the unit of power in si unit and provide you with units of power list in different measurement systems. So we see it is the power that has to do with the rate at which work is done. Here we can say that the bodybuilder has a higher power rating than the sixth-grader. If a bodybuilder and a sixth-grader carry a weight of 10 kgs up a flight of stairs, then the bodybuilder would most likely take less time than the sixth-grader to finish the same job. Sometimes the work is done quickly, and other times it might be slow and take longer. Work done is not determined by the amount of time the force took to cause the displacement. This page uses Creative Commons Licensed content from Wikipedia ( view authors).In Physics, work is done when a force acting on an object results in its displacement. Nelson, Robert A., ' The International System of Units Its History and Use in Science and Industry'.But when an SI unit is spelled out, it should always be written in lowercase (watt), unless it begins a sentence or is the name 'degrees Celsius'. As for all SI units whose names are derived from the proper name of a person, the first letter of its symbol is uppercase (W). For example, a nuclear power plant might use a fission reactor to generate heat (thermal output) which creates steam to drive a turbine to generate electricity.

SI prefixes can be used, for example megawatt thermal (MWt) and gigawatt thermal (GWt). This is a term that refers to thermal power produced. SI prefixes can be used, for example megawatt electrical (MWe) and gigawatt electrical (GWe). Watt electrical (abbreviation: We) is a term that refers to power produced as electricity. These units are often used in the context of power plants and home energy bills.įor the use of watts as a measurement of transmitter power in radio, see effective radiated power and nominal power. For example, a kilowatt hour, is the amount of energy expended by a one kilowatt device over the course of one hour it equals 3.6 megajoules (1 hour = 3600 seconds). When paired with a unit of time the term watt is used for expressing energy consumption. 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 Conférence Générale des Poids et Mesures in 1960.ĭerived and qualified units for power distribution Ī watt is a unit of power or the amount of energy per unit time. One watt is one joule of energy per second.ġ W = 1 J/s = 1 newton meter per second = 1 kg

4 Derived and qualified units for power distribution.

Watts units