Introduction

Energy is described as the “potential to conduct work” or the “ability to apply a force that causes an item to move.” Despite this complex definition, the meaning is simple and clear: energy is the force that makes objects move. Potential and kinetic energy are the two forms of energy. The best way to think about potential and kinetic energy is that potential energy arises before and kinetic energy occurs during an action. Consider that you’re carrying your physics textbook in the air. Because of its lofty elevation, it has the potential to fall. When you drop your textbook, the potential energy of motion is converted energy, which is the energy that drives the movement.

What is energy?

For all living organisms on the earth, energy is the most basic form of life. In this world, there are various types of energy. The Sun is considered the elemental form of energy in the earth. We can define energy as the ability to perform any physical action. Energy is a measurable property that can neither be created nor be destroyed and only transferred from one object to another. As a result, they claim that energy is the ability to work. The Joule is the SI unit of energy.

The Law of conservation of energy states that “Energy cannot be produced or destroyed; it can only be changed from one form to another,” according to the rules of conservation of energy.

Units of Energy

As per the International standards of Units, Joule is the unit used to measure energy. The word Joule is derived from the name of the former scientist James Prescott Joule. A joule is a derived unit and it is equivalent to the expended energy in applying the force of unit/one newton through the distance of one metre. Apart from Joule, the energy is also measured in calories, kilowatt-hours, ergs, kilocalories and British Thermal Units, which needs a conversion factor while expressing in the SI units.

Different forms of the energy

Energy comes in various forms. The most common types of energy are:-

• mechanical energy
• chemical energy
• muscular energy
• thermal energy
• light energy
• electrical energy
• nuclear energy
• Mechanical Energy: Mechanical energy is the energy produced by an object’s movement or location. The total kinetic and potential energy is mechanical. Examples: An object with mechanical energy has both potential and kinetic energy. However, one of the forms may have zero energy. Kinetic energy exists in a moving vehicle. There is potential and kinetic energy in moving a vehicle up a mountain. A book lying on the table has the potential energy.
• Thermal energy: The heat or thermal energy shows the temperature change between two networks. For example, a glass of warm tea has thermal energy with your surroundings.
• Nuclear Energy: The energy produced by changes in nuclear reactions of atomic nuclei. Example: Nuclear fusion, nuclear decay and Nuclear fission are examples of nuclear energy. 
• Chemical Energy: This form of energy is produced when molecules or atoms react chemically. Chemical energy comes in many forms, including chemiluminescence and electrochemical energy. Example: A battery or electrochemical cell is the best example of chemical energy.
• Electromagnetic Energy: It is the form of energy produced from electromagnetic waves or light. Example: Radio, x-rays, gamma rays, ultraviolet light and microwaves are the most common examples of E.M energy.
• Sonic Energy: It is an example of sound energy. Sound is the type of energy that needs a medium such as air, objects etc., to propagate. Example: When we talk to each other, we produce sound energy. 
• Gravitational Energy: Gravitational energy is one of the most crucial forces of attraction between two particles. Example: There is a presence of atmosphere in the earth due to the gravitational energy.
• Kinetic Energy is the form of energy that occurs due to motion. The range of kinetic energy is between 0 to infinite positive value. Example: When a kid is sitting in the swing, there is always kinetic energy, whether the swing moves upward or backwards.
• Potential Energy: The potential energy is the energy due to rest. Example: When we throw a ball towards the sky at the peak point, the ball’s potential energy gets to its maximum point and after that, the ball attends the kinetic energy and starts dropping down.

Law of conservation of energy

The Conservation Law of Energy explains that “the energy could neither be created nor destroyed and it can only transform from a single form to another. It denotes that the energy will remain uniform throughout the system unless additional energy is added from outside. It indicates that a variable always remains constant in an equation over time. Its value will remain the same before and after an event.

Conclusion

In the above chapter, we have read about the definition and types of energy. Energy is one of the essential components necessary for the survival of humans on earth. Our power produces energy but converts the food into vital nutrients by digestion. Our earth holds the atmosphere due to the presence of gravitational energy. Apart from this, energy is also classified as renewable, such as solar, electrical etc. and nonrenewable energy, such as coal, petroleum etc.