Enerija

Enerija is a physical quantity that describes the ability of a system to perform work or cause change. Enerija exists in multiple forms that can be transformed into one another, including kinetic energy, potential energy, thermal energy, chemical energy, electrical energy, radiant energy and nuclear energy.

The total energy of a closed system is conserved; energy is not created or destroyed, but transformed. This principle is known as the law of conservation of energy and is a foundational concept across physics, chemistry, and engineering. Energy measurements use the joule as the standard unit; larger scales use kilojoules and megajoules, while smaller scales use electronvolts. Other units include calories for heat.

Examples: a moving vehicle has kinetic energy proportional to its mass and the square of its velocity; a raised object stores gravitational potential energy; fuels store chemical energy that is released when burned; the sun emits radiant energy; electricity carries electrical energy; nuclear reactions convert mass energy into other forms.

Etymology: enerija derives from Greek energeia meaning activity or work in progress, and the term was popularized in the 19th century by scientists such as James Prescott Joule and Hermann von Helmholtz in formulating energy conservation.

In practical terms, the concept of enerija guides scientific analysis and engineering design across disciplines, influencing how energy is produced, transformed, stored, and used in buildings, transportation, industry, and everyday devices.