Understanding energy sources

All around us, including we humans, energy is one of the common things that occur. Energy is vast, because it takes place in almost every application, starting we ourself, that is the energy we use in surviving, the energy we get from food. There is a different source of energy today that allows human civilization to function. Most of the energy is gets from fossil fuels nuclear fuel, or renewable energy, although these energies are used to produce other forms of energy such as mechanical energy electrical energy, etc. This is why the study of energy is very necessary to learn and understand.

Today you’ll get to know the definition, use, importance, examples, types, and forms of energy. You’ll also get to know the unit of measure, transformation, conservation of energy, etc.

Read more: Understanding renewable energy



What is energy?

Energy can be defined as the ability of a physical system to perform work, that is, a system possesses energy when it has the ability to do work. In other words, energy is transferred or transformed whenever work is done. However, the exitance of energy in a system does not mean it’s necessarily available to do work.

In physics, energy is known to be the quantitative property that must be transferred to a body or physical system to perform work on the body or to heat it. Energy is a conserved quantity, which brought us to the law of conservation of energy. This law states that energy can be converted in form, but can neither be created nor destroyed.

All types of energy are of two forms which include the kinetic energy of a moving object and potential energy stored by an object’s position in a force field. The unit of measurement of energy is called joule.

I want you to understand energy as the following:

  • a scalar quantity
  • abstract and cannot always be perceived
  • given meaning through calculation
  • a central concept in science

Read more: Understanding Non-renewable energy resources

Uses and importance of energy

There are three basic uses and importance energy offers to we human, which include residential uses, commercial uses, and transportation uses.

Residential uses of energy:

This is the most common way energy is consumed, because they serve our daily home activities such as watch television, heating and lighting the home, taking shower, washing clothes, working from home on your computer or laptop, running appliances, cooking, etc. Almost forty percent of total energy use globally is for residential purposes. Although, it is the common way energy is also wasted. This is a result of the lack of education offered to the public over how to conserve energy use daily.

Commercial uses:

The commercial uses include heating, cooling, and lighting of commercial buildings and spaces, power used by organizations and businesses. The use of energy here is more or less similar to the use in the industrial space save for personal uses.

Transportation uses:

This side of energy consumption wholly dependent on energy, that is, over seventy percent of petroleum is used in the transport sector. The transport sector includes all vehicles from personal cars to trucks to buses and motorcycles. It also includes aircraft, ships, trains, and pipelines.

The following are the common importance of energy around us:

  • Energy powers communications, transportations, computers cutting-edge medical equipment, etc.
  • Energy support economic and social progress, building a better quality of life.
  • Reliable and affordable energy allows the products and services that enrich and extend life.
  • Energy can improve and even save lives.
  • It supports expanded industry, modern agriculture, increased trade, and improved transportation.
  • It creates better lives and reduces poverty.

Read more: Various types of energy and their examples

Forms and types of energy

There are different forms of energy that exist, they are all categorized into kinetic or potential. The energy associated with motion is known as kinetic energy, while potential energy is an energy associated with position but it is not “stored energy”.

kinetic energy

  • kinetic energy — motion
    • mechanical energy — motion of macroscopic systems
      • machines
      • wind energy
      • wave energy
      • sound (sonic, acoustic) energy
    • thermal energy — motion of particles of matter
      • geothermal energy
    • electric energy — motion of charges
      • household current
      • lightning
    • electromagnetic radiation — disturbance of electric and magnetic fields (classical physics) or the motion of photons (quantum physics)
      • radio, microwaves, infrared, light, ultraviolet, x-rays, gamma rays

solar energy

Read more: Forms of energy: kinetic and potential energy

potential energy

  • potential energy — position or arrangement
    • gravitational potential energy
      • roller coaster
      • waterwheel
      • hydroelectric power
    • electromagnetic potential energy
      • electric potential energy
      • magnetic potential energy
      • chemical potential energy
      • elastic potential energy
    • strong nuclear potential energy
      • nuclear power
      • nuclear weapons
    • weak nuclear potential energy

radioactive decay

Heat, kinetic or mechanical energy, light, potential energy, and electrical energy are the various forms in which energy exists.

Heat is also known as thermal energy from the movement of atoms or molecules. It may be considered as energy relating to temperature.

Kinetic energy is the energy of motion. A good example a swinging pendulum bob.

Potential energy is due to an object’s position. A good example is a ball sitting on a table with respect to the floor because gravity acts upon it.

Mechanical energy is the sum of kinetic energy and the potential energy of a body.

Light energy is available as photons.

Electrical energy is energy from the movement of charged particles like protons, electrons, or ions.

Magnetic energy is a form of energy obtained from a magnetic field.

Chemical energy is released or obtained from chemical reactions, produced by breaking or forming chemical bonds between atoms and molecules.

Nuclear energy is energy from interactions with the protons and neutrons of an atom. A good example is energy released by fission and fusion.

Units of energy

The SI unit of energy is the joule (J) or newton-meter (N * m). The joule is also the SI unit of work. It is named after James Prescott Joule who independently discovered the mechanical equivalent in a series of experiments. The SI unit of energy rate (energy per unit time) is the watt, which is a joule per second.

Energy Transformation

There is various form of energy transformation, which may occur at various efficiencies. The items that transform between these forms are known as transducers. A good example of transducers includes a battery, whose transformation takes place from chemical energy to electrical energy. A dam transforms from gravitational potential energy to kinetic energy of moving water and also blades of a turbine. Also, electrical energy through an electric generator or a heat engine.

Good examples of energy transformation include electric energy generation from energy through a steam turbine or lifting an object against gravity using electrical energy driving a crane motor. The lifting against gravity does mechanical work on the object and stores gravitational potential energy in the object. The falling of the object to the ground, allows mechanical work to be performed by gravity on the object. This transforms the potential energy in the gravitational field to the kinetic energy released as heat on impact with the ground.

Another good example of energy is the sun, which transforms nuclear potential energy into other forms of energy. Although its total mass does not decrease since it still contains the same total energy even when it occurs in different forms. However, its mass will decrease when the energy escapes out to its surrounding, largely as radiant energy.

Watch the video below to learn more on energy transformation:

An experiment has shown that there are limits to how heat can efficiently be converted into work in a cyclic process, e.g., in a heat engine. Carnot’s theorem and the second law of thermodynamics highly elucidate that. Despite that, some energy transformations are highly efficient, even though there some factors to be considered. Entropy helps us determine the direction of transformations in energy (what kind of energy is transformed and to what type)

Conservation of energy

Just as earlier stated, the law of conservation of energy says energy can neither be created nor be destroyed. The first law of thermodynamics state that a closed system’s energy is constant unless energy is transferred in or out by work or heat, and that no energy is lost in the transfer. This is to say, the total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system. The total energy of a system will always remain constant if someone measures or calculates the total energy of a system of particles whose interactions do not depend on time.

A good example is when two billiard balls colliding, which may come to rest, with the resulting energy becoming sound and maybe little heat at the point of collision. There is kinetic energy when the balls are in motion. They have potential energy whether in motion or stationary because they are on a table above the ground.

One of the common forms of energy transformation is the conversion of heat into work in a reversible isothermal expansion of an ideal gas. The second law of thermodynamics states that the system doing work always loses some energy as waste heat. This creates a limit to the amount of heat energy that can do work in a cyclic process. Although, mechanical and other forms of energy can be transformed in the other direction into thermal energy without such limitations. The total energy of a system can be calculated by adding up all forms of energy in the system.


Energy is the ability of a physical system to perform work, that is, a system possesses energy when it has the ability to do work. In other words, energy is transferred or transformed whenever work is done. That is all for this post where the definition, use, importance, examples, types, and forms of energy is being discussed. You also learned the unit of measure, transformation, conservation of energy.

I hope you get enough from the reading, if so, kindly share with other students. Thanks for reading, see you next time!


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