Engineering

Using heating systems to provide effective cooling

Climate change is causing a persistent increase in the number of hot summer days. Offices and homes are getting hotter, and the nights bring little respite from the heat. Against this backdrop, a significant increase in new ...

Hi Tech & Innovation

Explainer: The tech behind Tokyo Olympics' fast track

The Jamaican sprinter and her Olympic-record time captured everyone's attention. What's under foot, though, might have been a factor when Elaine Thompson-Herah broke a 33-year-old Olympic record in the women's 100 meters.

Energy & Green Tech

Research illuminates how energy costs vary nationwide

Costs for energy are borne unequally across the U.S. population. Argonne research is providing key data that can help inform decisions about which technologies can reduce disparities.

Energy & Green Tech

Form Energy announces Iron-Air 100-hour storage battery

Officials with battery maker Form Energy have announced the development of the Iron-Air 100-hour storage battery—a battery meant to store electricity created from renewable sources such as solar and wind. As part of their ...

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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.

This text uses material from Wikipedia, licensed under CC BY-SA