enerji

Enerji refers to the ability to perform work or produce change in a system. In physics, energy is a conserved quantity that can take many forms, including kinetic energy, potential energy, thermal energy, chemical energy, electrical energy, radiant energy, and nuclear energy. The SI unit of energy is the joule (J); power is the rate of energy transfer and is measured in watts (W). One kilowatt-hour equals 3.6 million joules.

Energy can be transformed from one form to another, often with efficiency losses due to friction or resistance. Examples: a falling object converts potential to kinetic energy; photosynthesis stores chemical energy; electrical energy powers devices; thermal energy relates to temperature. In closed systems, total energy remains constant.

In society, energy systems consist of production, transformation, delivery, and use. Primary energy sources include fossil fuels, nuclear, and renewables such as solar, wind, hydro, and geothermal. Energy policy addresses reliability, affordability, and environmental impact, including greenhouse gas emissions. Efficiency measures and decarbonization strategies aim to reduce emissions while meeting demand.