US-European differences on climate law persist

President Joe Biden on Thursday tried to allay concerns raised by French President Emmanuel Macron about a clean energy law that benefits electric vehicles and other products made in North America. But the U.S. and Europe ...

Why walking on deforming surfaces uses more energy

A team of researchers at the University of Liverpool's Institute of Life Course & Medical Sciences, working with a colleague from Liverpool John Moores University, has discovered why people use more energy when walking on ...

New monochromator optics for tender X-rays

A climate-neutral energy supply requires a wide variety of materials for energy conversion processes, for example catalytically active materials and new electrodes for batteries. Many of these materials have nanostructures ...

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Energy

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.

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