Energy & Green Tech

UN agency: North Europe radiation likely linked to reactor

The U.N. nuclear agency said Friday that slightly elevated levels of radioactivity detected in northern Europe likely were related to a nuclear reactor that was either operating or undergoing maintenance, but it's still unclear ...

Robotics

Team develops remote specimen collection robot

The Korea Institute of Machinery & Materials (KIMM) under the Ministry of Science and ICT developed a remote specimen collection robot that eliminates direct contact between medical personnel and patients.

Energy & Green Tech

Clean energy revolution may leave disadvantaged communities behind

Historically disadvantaged communities in Los Angeles County are at risk of getting left behind in the transition to lower-carbon energy sources and energy-efficient technologies, according to a new study by the California ...

Energy & Green Tech

Dye-sensitized solar cells that adapt to different light conditions

Solar cells made of semi-transparent photovoltaic (PV) materials typically have a fixed optical transmission, which results in either high transparency or high efficiency, but rarely both. In order to perform optimally when ...

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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