energiya

Energiya is the term used in many languages to denote energy, a fundamental quantity in physics that describes the capacity to do work or cause physical change. The word derives from Greek energeia, meaning activity, and has entered languages through Latin and French. In physics, energy occurs in multiple forms and can be stored, transformed, or transferred between objects and systems without altering the total amount in an isolated system.

Common forms include kinetic energy (associated with motion), potential energy (related to position in a field), thermal energy (linked to temperature and microscopic motion), chemical energy, electrical energy, radiant energy (light and electromagnetic radiation), and elastic energy. The first law of thermodynamics states that energy is conserved in isolated systems; it can be converted from one form to another, with some losses often appearing as heat or entropy increase. Energy is measured in joules in the International System of Units, with larger amounts expressed in kilojoules or megajoules; electrical energy is also commonly expressed in watt-hours or kilowatt-hours.

Energy plays a central role in science, engineering, technology, and policy. Understanding energy flows, transformation efficiencies, and the availability of energy resources underpins fields ranging from mechanics and thermodynamics to climate science and sustainable development.