Energy

Energy is the ability to produce change or perform work. It is one of the fundamental concepts in physics because every movement, physical process and natural phenomenon involves energy being transferred or transformed. Energy cannot be created or destroyed, only converted from one form to another. This principle is known as the law of conservation of energy.

Common forms include kinetic energy, associated with motion; potential energy, stored because of position or shape; thermal energy, related to the motion of particles; chemical energy, stored in substances such as food and fuels; electrical energy; radiant energy carried by light; and nuclear energy, stored within atomic nuclei. The standard unit used to measure energy is the joule, although other units are used in specific fields, such as the kilowatt-hour for electrical consumption.

Energy constantly changes form in everyday life. A moving bicycle converts chemical energy from the rider's muscles into kinetic energy, while friction gradually transforms part of that energy into heat. A power station converts energy from water, wind, sunlight, fossil fuels or nuclear reactions into electricity, which can later become light, sound, heat or mechanical motion in homes and industries.

Living organisms also depend on continuous energy transformations to grow, move and maintain their vital functions. Scientists and engineers work to improve energy efficiency, reducing waste while producing the same useful result. Understanding how energy flows and changes helps explain natural phenomena, supports technological innovation and plays an important role in building more sustainable energy systems.