Question

what is energy?

Answer 1

Energy is the capacity of a physical system to perform work. Energy can be converted in various forms but not created or destroyed. The various forms of energy are solar, wind, hydro, nuclear, thermal, sound, chemical etc. There is no absolute measure of energy because energy is defined as the ability to do work on objects. The law of conservation of energy states that the total energy of a system can only change if energy is transferred into or out of the system. The SI unit of energy is the joule (J) or newton-meter (N * m).