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Energy

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In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working") is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, light, elastic, and electromagnetic energy. The forms of energy are often named after a related force.

Any form of energy can be transformed into another form, but the total energy always remains the same. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the Earth.

For more information about Energy, read the full article at Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.


News tagged with energy

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ORNL 'deep retrofits' can cut home energy bills in half

ORNL 'deep retrofits' can cut home energy bills in half

Technology / Energy

created Nov 25, 2009 | popularity 3.7 / 5 (3) | comments 0

(PhysOrg.com) -- Oak Ridge National Laboratory has announced plans to conduct a series of deep energy retrofit research projects with the potential to improve the energy efficiency in selected homes by as ...


Sustainable Corn Production Supports Advanced Biofuel Feedstocks

Sustainable Corn Production Supports Advanced Biofuel Feedstocks

Biology / Biotechnology

created Nov 25, 2009 | popularity 3.3 / 5 (3) | comments 0

(PhysOrg.com) -- Researchers worldwide are trying to economically convert cellulosic biomass such as corn stover into "cellulosic ethanol." But Agricultural Research Service (ARS) scientists have found that ...


Seeking a Smarter Grid: Integrating Wind Energy by Linking Buildings to the Grid

Seeking a Smarter Grid: Integrating Wind Energy by Linking Buildings to the Grid

Technology / Energy

created Nov 24, 2009 | popularity not rated yet | comments 0

In utility parlance, wind energy is known as a “variable load.” That’s because wind is naturally unpredictable and inconstant. What’s worse, it is more likely to blow at night, when demand for electricity ...


NREL Uncovers Clean Energy Leaders State by State

NREL Uncovers Clean Energy Leaders State by State

Technology / Energy

created Nov 24, 2009 | popularity 3 / 5 (4) | comments 2

(PhysOrg.com) -- That California and Texas still lead the United States in generating renewable energy probably is no surprise. But, NREL's 2009 State of the States report shows that several smaller states ...


Invention will help speed development of drug treatments for heart failure

Medicine & Health / Research

created Nov 23, 2009 | popularity not rated yet | comments 0

Research conducted by University of Minnesota scientists, in collaboration with Celladon Corporation, has led to the invention of technology to more rapidly identify compounds for the treatment of heart failure.


Workers at the Statkraft Osmotic power plant prototype in Tofte

Harnessing the power of salt, Norway tries osmotic power

Technology / Energy

created Nov 23, 2009 | popularity 3.8 / 5 (4) | comments 4

After wind, sun, currents and tides, a company is preparing to make clean electricity by harnessing another natural phenomenon, the energy-unleashing encounter of freshwater and seawater.


How green is your house? Recycling favorite activity among Brits says new survey

Space & Earth / Environment

created Nov 23, 2009 | popularity 1 / 5 (1) | comments 3

Seventy percent of households always separate their rubbish for recycling, but only 2 percent buy their energy on a green tariff, according to the early findings of a major new annual household survey, called "Understanding ...


Is global warming unstoppable?

Space & Earth / Environment

created Nov 23, 2009 | popularity 3.7 / 5 (31) | comments 31

In a provocative new study, a University of Utah scientist argues that rising carbon dioxide emissions - the major cause of global warming - cannot be stabilized unless the world's economy collapses or society builds the ...


Generating electricity from air flow

Physics / General Physics

created Nov 22, 2009 | popularity 3.3 / 5 (10) | comments 2

A group of researchers at the City College of New York is developing a new way to generate power for planes and automobiles based on materials known as piezoelectrics, which convert the kinetic energy of motion into electricity. ...


China is the world's largest emitter of the greenhouse gases blamed for global warming

China harnesses mountain wind power

Technology / Energy

created Nov 22, 2009 | popularity 4.4 / 5 (12) | comments 3

In the mountains above the southwestern Chinese town of Dali, dozens of new wind turbines dot the landscape -- a symbol of the country's sky-high ambitions for clean, green energy.


NJIT receives funding to improve Big Bear Telescope, study solar energy

NJIT receives funding to improve Big Bear Telescope, study solar energy

Space & Earth / Astronomy

created Nov 20, 2009 | popularity 4.6 / 5 (5) | comments 1

NJIT researchers are at work on many scientific and technological frontiers. The National Science Foundation has recently provided support that totals nearly $4.3 million for the diverse efforts of the following ...


Flax and yellow flowers can produce bioethanol

Flax and yellow flowers can produce bioethanol

Technology / Energy

created Nov 20, 2009 | popularity 1 / 5 (1) | comments 0

Surplus biomass from the production of flax shives, and generated from Brassica carinata, a yellow-flowered plant related to those which engulf fields in spring, can be used to produce bioethanol. This has be ...


Using superconducting probes to get a picture of what it's like inside CNTs

Nanotechnology / Nanophysics

created Nov 20, 2009 | popularity 4.4 / 5 (9) | comments 0

(PhysOrg.com) -- "Carbon nanotubes are exciting for fundamental physics, and for potential technological applications," Nadya Mason tells PhysOrg.com. "However, we are generally limited in the way that we can study them. ...


Hunting for Planets in the Dark

Hunting for Planets in the Dark

Space & Earth / Astronomy

created Nov 19, 2009 | popularity 4.8 / 5 (4) | comments 5

A proposed space mission that aims to measure dark energy could also detect planets that current surveys are unable to find.


Nanotube defects equal better energy and storage systems

Nanotube defects equal better energy and storage systems

Nanotechnology / Nanomaterials

created Nov 19, 2009 | popularity 4.4 / 5 (10) | comments 2

(PhysOrg.com) -- Most people would like to be able to charge their cell phones and other personal electronics quickly and not too often. A recent discovery made by UC San Diego engineers could lead to carbon ...