Question

Give the main categories of source of energy?

Answer 1

This article is about the scalar physical quantity. For an overview of and topical guide to energy, see Outline of energy. For other uses, see Energy (disambiguation)."Energetic" redirects here. For other uses, see Energetic (disambiguation).The Sun is the source of energy forlife on Earth. It releases mainly thermal energy, heat energy and radiant (light) energy.

In physics, energy is a property of objects which can be transferred to other objects or converted into different forms.[1] The "ability of a system to perform work" is a common description, but it is misleading because energy is not necessarily available to do work.[2] For instance, in SI units, energy is measured in joules, and one joule is defined "mechanically", being the energy transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton.[note 1] However, there are many other definitions of energy, depending on the context, such as thermal energy, radiant energy, electromagnetic, nuclear, etc., where definitions are derived that are the most convenient.