Joule
| Topics: |
| SI multiples of joule | ||||||
|---|---|---|---|---|---|---|
| Multiple | Name | Symbol | Multiple | Name | Symbol | |
| 100 | joule | J | ||||
| 101 | decajoule | daJ | 10–1 | decijoule | dJ | |
| 102 | hectojoule | hJ | 10–2 | centijoule | cJ | |
| 103 | kilojoule | kJ | 10–3 | millijoule | mJ | |
| 106 | megajoule | MJ | 10–6 | microjoule | µJ | |
| 109 | gigajoule | GJ | 10–9 | nanojoule | nJ | |
| 1012 | terajoule | TJ | 10–12 | picojoule | pJ | |
| 1015 | petajoule | PJ | 10–15 | femtojoule | fJ | |
| 1018 | exajoule | EJ | 10–18 | attojoule | aJ | |
| 1021 | zettajoule | ZJ | 10–21 | zeptojoule | zJ | |
| 1024 | yottajoule | YJ | 10–24 | yoctojoule | yJ | |
Definition
The joule (symbol: J) SI unit of work or energy, defined to be the work done by a force of one newton acting to move an object through a distance of one meter in the direction in which the force is applied. Equivalently, since kinetic energy is one half the mass times the square of the velocity, one joule is the kinetic energy of a mass of two kilograms moving at a velocity of 1 m/s. As a rough guide, 1 joule is the absolute minimum amount of energy required to lift a one kilogram object up by a height of 10 centimeters on the surface of the Earth.
History
The unit is named for James Prescott Joule (1818-1889), the English physicist who made fundamental contributions to the study of heat and energy. Joule determined the mechanical equivalent of heat by measuring change in temperature produced by the friction of a paddlewheel attached to a falling weight in the 1840s.
Conversions
| from / to |
Joule |
kilowatt-hour | electronvolt | Btu | horsepower hour |
foot-pound | |||
|---|---|---|---|---|---|---|---|---|---|
|
1 Joule |
1 | 0.278 · 10?3 | 6.241 · 1018 | 0.2388 | 9.4782 · 10?4 | 3.7251 · 10-7 | 0.7376 | 1 · 107 | 9.4782 · 10?9 |
| 1 kilowatt-hour | 3.6 · 106 | 1000 | 22.5 · 1024 | 8.5985 · 105 | 3.4121 · 103 | 1.3410 | 2.6552 · 106 | 3.6 · 1013 | 0.0341 |
| 1 electronvolt | 0.1602 · 10?18 | 44.5 · 10?27 | 1 | 3.8267 · 10?20 | 1.5186 · 10?22 | 5.9682 · 10?26 | 1.1817 · 10?19 | 1.6022 · 10?12 | 1.5186 · 10?27 |
|
1 calorie |
4.1868 | 1.163 · 10?3 | 0.261 · 1018 | 1 | 3.9683 · 10?3 | 1.56 · 10?6 | 3.0880 | 4.186 · 107 | 3.9683 · 10?8 |
| 1 Btu | 1.055 · 103 | 0.293 | 6.585 · 1021 | 251.996 | 1 | 3.9302 · 10?4 | 778.169 | 1.05435 · 1010 | 1 · 10?5 |
| 1 horsepower-hour | 2.6845 · 106 | 745.60 | 1.6755 · 1025 | 6.4119 · 105 | 2.5444 · 103 | 1 | 1.98 · 106 | 2.6845 · 1013 | 2.5444 · 10-2 |
| 1 foot-pound | 1.3558 | 3.7662 · 10-4 | 8.4623 · 1018 | 0.3238 | 1.2851 · 10-3 | 5.0505 · 10-7 | 1 | 1.3558 · 107 | 1.2851 · 10-8 |
| 1 · 10-7 | 2.7778 · 10-11 | 6.2415 · 1011 | 2.4 · 10-8 | 9.4782 · 10-11 | 3.7251 · 10-14 | 7.4 · 10-8 | 1 | 9.4782 · 10-16 | |
|
1 therm |
1.0551 · 108 | 2.9307 · 104 | 6.5851 · 1026 | 2.520 · 107 | 1 · 105 | 39.301 | 7.7817 · 107 | 1.0551 · 1015 | 1 |
Further reading
- How Many? A Dictionary of Units of Measurement, Russ Rowlett, Center for Mathematics and Science Education, University of North Carolina at Chapel Hill
- SI base units and SI derived units, the Physics Laboratory, National Institute of Standards and Technology
- Energy conversion tool at unitconversion.org
