Robotics

Engineers find ankle exoskeleton aids running

Running is great exercise but not everyone feels great doing it. In hopes of boosting physical activity—and possibly creating a new mode of transportation—engineers at Stanford University are studying devices that people ...

Energy & Green Tech

Electric cars better for climate in 95% of the world

Fears that electric cars could actually increase carbon emissions are unfounded in almost all parts of the world, news research shows. Media reports have regularly questioned whether electric cars are really "greener" once ...

Engineering

New computer program predicts crack initiation in 3-D

Most structures and materials have defects, and if the conditions are right, these defects can lead to the initiation and propagation of cracks. Finding out where and with what orientation a surface crack is most likely to ...

Energy & Green Tech

Deep learning cuts costs in building control

American buildings consume roughly 40 percent of U.S. energy, much of which is expended on heating, cooling, and ventilation. Enhanced control methods can help reduce energy consumption. Model Predictive Control (MPC) has ...

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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