The International Bureau of Weights and Measures defined the joule as work done when a force moves an object one metre. This definition anchors energy to three base units: kilogram, metre, and second.
Wilhelm Siemens proposed the unit during his inauguration speech on the 23rd of August 1882. The second International Electrical Congress officially adopted the name on the 31st of August 1889.
Heating 0.239 grams of water from zero degrees Celsius to one degree consumes exactly one joule. Scientists use these relationships to measure everything from lifting weights to powering circuits.
Energy is a scalar quantity formed by the dot product of force and displacement vectors while torque acts as a vector created by the cross product of force and distance vectors. The General Conference on Weights and Measures named the energy unit joule but did not assign a special name to the torque unit.
A thermochemical calorie equals 4.184 joules and an International Table calorie measures 4.1868 joules. One watt-hour contains 3,600 joules and a kilowatt-hour holds 3.6 million joules.