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  2. Renewable energy - Wikipedia

    en.wikipedia.org/wiki/Renewable_energy

    Renewable energy (or green energy) is energy from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, and hydropower. Bioenergy and geothermal power are also significant in some countries. Some also consider nuclear power a renewable power source ...

  3. Energy - Wikipedia

    en.wikipedia.org/wiki/Energy

    The word energy derives from the Ancient Greek: ἐνέργεια, romanized: energeia, lit. 'activity, operation', [4] which possibly appears for the first time in the work of Aristotle in the 4th century BC. In contrast to the modern definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness ...

  4. Second law of thermodynamics - Wikipedia

    en.wikipedia.org/wiki/Second_law_of_thermodynamics

    t. e. The second law of thermodynamics is a physical law based on universal empirical observation concerning heat and energy interconversions. A simple statement of the law is that heat always flows spontaneously from hotter to colder regions of matter (or 'downhill' in terms of the temperature gradient).

  5. First law of thermodynamics - Wikipedia

    en.wikipedia.org/wiki/First_law_of_thermodynamics

    v. t. e. The first law of thermodynamics is a formulation of the law of conservation of energy in the context of thermodynamic processes. The law distinguishes two principal forms of energy transfer, heat and thermodynamic work, that modify a thermodynamic system containing a constant amount of matter. The law also defines the internal energy ...

  6. Mass–energy equivalence - Wikipedia

    en.wikipedia.org/wiki/Mass–energy_equivalence

    In physics, mass–energy equivalence is the relationship between mass and energy in a system's rest frame, where the two quantities differ only by a multiplicative constant and the units of measurement. [1][2] The principle is described by the physicist Albert Einstein 's formula: . [3] In a reference frame where the system is moving, its ...

  7. Work (physics) - Wikipedia

    en.wikipedia.org/wiki/Work_(physics)

    In science, work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, for a constant force aligned with the direction of motion, the work equals the product of the force strength and the distance traveled. A force is said to do positive work if it has a component in the ...

  8. Energy policy of the United States - Wikipedia

    en.wikipedia.org/wiki/Energy_policy_of_the...

    The energy policy of the United States is determined by federal, state, and local entities. It addresses issues of energy production, distribution, consumption, and modes of use, such as building codes, mileage standards, and commuting policies. Energy policy may be addressed via legislation, regulation, court decisions, public participation ...

  9. Quizlet - Wikipedia

    en.wikipedia.org/wiki/Quizlet

    Quizlet is a multi-national American company that provides tools for studying and learning. [ 1 ] Quizlet was founded in October 2005 by Andrew Sutherland, who at the time was a 15-year old student, [ 2 ] and released to the public in January 2007. [ 3 ] Quizlet's primary products include digital flash cards, matching games, practice electronic ...