Energy is a quantifiable state function of every physical system. Energy allows one to predict how much work a physical system could be made to do, or how much heat it can exchange. In general, the presence of energy is detected by an observer or system any time there is a change in the properties of another object or system. This is where the early exploration of the nature of energy began. As our understanding of the nature of energy progressed, scientists found it to exist in many forms not readily observable by the average unaided observer. In fact, in some cases the presence of particular types of energy prevents changes from being easily observed in a particular object or system. Empirical observations have shown that the total quantity of energy is conserved. This makes the concept of energy very important in physics.

Subcategories

There are 6 subcategories to this category.

E

• Electric power
• Energy development

F

• Fuels

G

• Green vehicles

R

• Renewable energy

U

• Units of energy

Articles in category "Energy"

There are 40 articles in this category.

Energy A Animal traction C CEEETA Characteristic energy Conservation of energy Current solar income D Distributed generation E EU energy label Electric vehicle Electron affinity Energy Tax Act Energy conservation Energy conversion

E cont. Enthalpy F Fuel Fuel efficiency G Gibbs free energy H Heat Hybrid car Hydrogen car Hydrogen economy I Internal energy Ionization energy K Kinetic energy M Musicians United for Safe Energy N Net energy gain O Orders of magnitude (energy)

P Soft energy path Potential energy Power beaming R Radiant energy Renewable energy Renewable energy development Rotational energy S Solar radiation Star rating T TPE The Hype about Hydrogen U United States Enrichment Corporation W Mechanical work