How slippery surfaces allow sticky pastes and gels to slide

An MIT research team that has already conquered the problem of getting ketchup out of its bottle has now tackled a new category of consumer and manufacturing woe: how to get much thicker materials to slide without sticking ...

New technique produces longer-lasting lithium batteries

The grand challenge to improve energy storage and increase battery life, while ensuring safe operation, is becoming evermore critical as we become increasingly reliant on this energy source for everything from portable devices ...

Carbon-negative power generation for China

If we're going to limit global temperature increases to 2 degrees above pre-industrial levels, as laid out in the Paris Climate Agreement, it's going to take a lot more than a transition to carbon-neutral energy sources such ...

Transparent wood can store and release heat

Wood may seem more at home in log cabins than modern architecture, but a specially treated type of timber could be tomorrow's trendy building material. Today, scientists report a new kind of transparent wood that not only ...

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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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