Énergie

Énergie, also commonly anglicized as energy, is a fundamental concept in physics and is broadly defined as the capacity to do work. In more precise terms, it is a conserved property of physical systems; the law of conservation of energy states that energy can be converted in form, but not created or destroyed.

Energy exists in many forms, each of which can be converted into the others. These forms include:

• Kinetic energy: The energy of motion. Any object in motion has kinetic energy.
• Potential energy: The energy an object has due to its position or configuration. Examples include gravitational potential energy (due to height), elastic potential energy (due to stretching or compression), and chemical potential energy (stored in chemical bonds).
• Thermal energy: The internal energy of a system due to the kinetic energy of its atoms or molecules. It is often associated with temperature.
• Chemical energy: Energy stored in the bonds of chemical compounds. This energy can be released during chemical reactions.
• Electrical energy: Energy associated with the flow of electric charge.
• Radiant energy: Energy that travels in the form of electromagnetic waves, such as light, radio waves, and X-rays.
• Nuclear energy: Energy stored within the nucleus of an atom. It can be released through nuclear reactions like fission and fusion.
• Mass energy: According to Einstein's famous equation E=mc², mass itself is a form of energy. A small amount of mass can be converted into a large amount of energy.

The standard unit of energy in the International System of Units (SI) is the joule (J). Other units of energy include the calorie (cal), the kilowatt-hour (kWh), and the British thermal unit (BTU).

Energy plays a vital role in virtually all aspects of the universe, from the smallest subatomic particles to the largest galaxies. It is essential for life, powering biological processes, and for technological advancements, powering machines and industries. The efficient management and utilization of energy resources are critical for sustainable development and addressing global challenges such as climate change.