# What Is Energy?

Energy is a concept that is derived from the Ancient Greek word energeia, which means activity or operation. The word first appears in Aristotle’s work in the 4th century BC, and describes a qualitative philosophical concept. Its definition includes pleasure and happiness. But what exactly is energy? What is its importance to our daily lives? And what is it used for? What are its different forms? Let’s find out.

## Potential energy

The definition of potential energy is the amount of energy stored in a system that can be changed. Potential energy arises in systems where mass and movement move in a certain direction. The mass and movement of a ball in a gravity-based system exert a force. This work transfers additional energy to the system, which is stored as gravitational potential energy. When we consider potential energy of a system, we can relate it to energy, work, and power.

## Kinetic energy

What is kinetic energy? Simply put, it’s the energy of motion, and it’s never negative. Kinetic energy is a scalar quantity that provides both magnitude and direction. A moving object’s kinetic energy can be converted to electrical energy or stored, depending on the method. Let’s examine a few of the most common methods for harnessing kinetic energy. In simple terms, bike lights utilize pedal power to illuminate a light bulb. Turbines, on the other hand, utilize the power of wind or water to generate electricity.

## Chemical potential energy

Chemical potential is the amount of energy that is added to a system when one particle is added to another. Chemical potential is typically noted as the sum of the chemical potential of the reactant and the product. This energy can be calculated using the partial pressure of the product and the chemical potential of the reactant, and the coefficients of the reaction (typically chosen as negative for reactants). The chemical potential is an ensemble of systems with the same energy and exchange energy with a large heat reservoir. This energy is stored in the chemical potential of the system, and the exchange of energy keeps it at a constant temperature.

## Elastic potential energy

Elastic potential energy is stored in a deformed object. This energy is equal to the work done to stretch the object. This potential energy depends on the spring constant, k, as well as the distance stretched. Hooke’s law states that the force needed to stretch a spring is proportional to the distance streched. You can find elastic potential energy in sponges, rubber bands, and bungee cords.

## Gravitational potential energy

The amount of energy a body exerts in response to gravity is known as gravitational potential energy. This is a scalar quantity that is a function of its position in three-dimensional space. The gravitational potential energy of two masses is the same. A gravitational field is also a scalar quantity. The gravitational potential energy of three objects should be the same. However, the magnitude of the gravitational force and the gravitational potential energy of three objects differ.