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Energy
hideIn 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
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News tagged with energy
CERN Colour X-ray Technology Set to Save Lives
17 hours ago |
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(PhysOrg.com) -- Medical studies are soon to start with the MARS scanner, a revolutionary CT scanner developed by the University of Canterbury, New Zealand. The scanner, which incorporates technology developed at the world's ...
New Bacterial Behavior Discovered
18 hours ago |
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(PhysOrg.com) -- Bacteria dance the electric slide, officially named electrokinesis by the USC geobiologists who discovered the phenomenon.
Search results for energy
Launch of first operating system for smart grid home automation
26 minutes ago |
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Fraunhofer IWES (Germany) presents the OGEMA Alliance, which will offer an open software platform for energy management.
New way to break some of the strongest chemical bonds
3 hours ago |
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(PhysOrg.com) -- Scientists at Cornell University in the U.S. have found a new way of breaking two of the strongest chemical bonds, at ambient temperature and pressure, and this breakthrough could lead to ...
Looking for the heartbeat of cellular networks
15 minutes ago |
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Our cells' molecules form an intricate network of interactions. Today's techniques, however, can only be used to measure individual molecular reactions outside the cells. Since molecular concentrations are much higher in ...
Icy moons of Saturn and Jupiter may have conditions needed for life
15 hours ago |
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(PhysOrg.com) -- Scientists once thought that life could originate only within a solar system's "habitable zone," where a planet would be neither too hot nor too cold for liquid water to exist on its surface. ...
Miracle light: Can lasers solve the energy crisis?
15 hours ago |
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Next year will mark the 50th birthday of the laser, one of the most productive and widely used mega-inventions of the last century. Scientists hope that 2010 also will see the launch of laser technology's greatest challenge: ...
Seattle Charges Up for Electric Cars
16 hours ago |
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(AP) -- Over the next two years, 2,500 charging stations for electric vehicles will be built in the Seattle area as part of a partnership between Nissan North America and the Electric Transportation Engineering ...
Micromachined piezoelectric harvester drives fully autonomous wireless sensor
16 hours ago |
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For the first time, a piezoelectric harvesting device fabricated by MEMS technology generates a record of 85μW electrical power from vibrations. A wafer level packaging method was developed for robustness. ...
Ecosystem, vegetation affect intensity of urban heat island effect
Space & Earth / Earth Sciences
16 hours ago |
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NASA researchers studying urban landscapes have found that the intensity of the "heat island" created by a city depends on the ecosystem it replaced and on the regional climate. Urban areas developed in arid and semi-arid ...
New results from a terra-ific decade in orbit
Space & Earth / Earth Sciences
17 hours ago |
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December 18, 2009, marks the tenth year since the launch of Terra, one of NASA's "flagship" Earth observing satellites. But the decade is more than just a mechanical milestone. With each additional day and ...
Naturally skinny people have their own challenges
14 hours ago |
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Nancy Brueheim wishes she could break 100 pounds. Without working at it, Brueheim, who is 71 and stands 5-foot-2, fluctuates between 95 and 98 pounds.
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