What Are the Main Forms of Energy in Physics?
Energy is the scalar quantity whose SI unit is given in "Joule." Energy is found in various things, and therefore there are different types of energy. All energy forms are either potential (energy that is stored) or kinetic (the energy of moving objects). It can be changed from one to another type, but it can be neither destroyed nor created.
This is something we have heard a hundred times from our teacher, but if we have asked what kind of work has to be accomplished to define the term energy, we can define it like this. Work is said to be accomplished, when an object is moved against a force, such as gravity.
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Different Forms of Energy
There are many different kinds of energy, which fall into two primary forms: potential and kinetic. Let us have a look at different forms of energy and examples.
Kinetic Energy
Kinetic energy can be defined as the energy of motion. If an object is in a moving state, it is said to have kinetic energy. Kinetic energy is one of the two primary energy forms - the other is the potential (so-called stored) energy. For example, flowing water, a moving ball, and more.
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The kinetic energy equation can be given by, ½ m x v²
Where v is the object velocity, and m is the object mass.
Potential Energy
Potential energy is the kind of energy stored within an object because of its arrangement, position, or state. This energy is one of the two primary forms of energy, along with kinetic energy.
It is measured by the amount of work done. A few examples are water in a lake, a pen on the table, and more.
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The potential energy equation can be given by, m x g x h
Where ‘m’ is the mass of the object in kilograms, ‘g’ is the acceleration due to gravity, and ‘h’ is the height in metres.
Mechanical Energy
The sum of potential and kinetic energy that is associated with the motion & the position of an object is called Mechanical energy. Therefore, we can derive the formula of mechanical energy as:
Mechanical Energy = Kinetic Energy + Potential Energy,
Mechanical energy = ½ m x v² + mgh
Chemical Energy
It is the energy that is stored in chemical compound bonds, such as molecules and atoms. In the same environment and given temperature, energy can either be released or absorbed due to the reaction between the set of chemical substances is equal to the difference between reactants and energy content of the products. When a chemical reaction takes place, this energy is released.
Once chemical energy has been released from a substance, usually, that substance then transforms into a new substance completely.
Some other types of energy are Magnetic, Electric, Nuclear, Radiant, Elastic, Ionisation, Thermal, Gravitational, and Heat & Mechanical work. Chemical energy can also be used in food and wood and stored in Biomass, Coal, Chemical batteries, and vehicle's airbags.
Light Energy
Light energy is a kind of electromagnetic radiation. Light consists of photons that are produced when the atoms of an object heat up. Light travels in waves, and it is the only form of energy visible to the human eye. This type of energy is also kinetic energy.
Light is made of photons, which are tiny packets of energy. When the atoms of an object heat up, photons are produced from the movement of atoms. The photons are produced depending on the heat of the object.
Heat or Thermal Energy
Thermal energy can also be called heat energy, which is produced when a rise in temperature causes molecules and atoms to move faster and collide with each other.
The energy that comes from the temperature of the heated substance is known as thermal energy.
Some examples of thermal energy are the warmth from the sun, A cup of hot chocolate, Baking in an oven, and the heat from a heater.
The below representation of boiling water on a stove shows the example of thermal energy.
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These are some of the energy forms and in addition to these, there are various forms of energy.
Different Types of Energy Resources
Energy sources are also used as fuels. These fuels are used in automobiles, machinery, and many other industries. They are used in the thermal plants to generate electricity. Energy resources can be further classified into two types as Non-renewable and Renewable. The types of energy sources are given below.
Non-Renewable Resources
Fossil fuels like natural gas, oil, and coal are called non-renewable energy resources because if these are used once, they cannot be renewed by natural processes or any means.
Renewable Resources
Natural resources like water, wind, geothermal, and solar are known as the types of renewable energy sources as they come from the sources that regenerate it back after consumption and are available in nature continuously.
Some energy types based on their resources are given below.
Coal
Bioenergy
Geothermal
Hydropower
Hydrogen
Nuclear
Natural Gas
Oil
Solar
Wood
Wind
FAQs on Types of Energy Explained with Examples
1. What are the two primary categories of energy in Physics?
In physics, energy is broadly classified into two primary categories: Kinetic Energy, which is the energy of motion, and Potential Energy, which is the energy stored within an object due to its position, state, or arrangement. All other forms of energy are essentially manifestations of these two fundamental types.
2. What are the main types of energy? Please provide examples.
There are several important types of energy that describe different physical phenomena. The main forms include:
- Mechanical Energy: The sum of kinetic and potential energy in an object. Example: A moving car or a roller coaster at the top of a hill.
- Thermal Energy: The internal energy of a system due to the temperature from the motion of its atoms and molecules. Example: The heat from a hot cup of tea.
- Chemical Energy: Energy stored in the bonds of chemical compounds. Example: The energy in batteries, food, or fuel like wood and coal.
- Electrical Energy: Energy carried by moving electrons in an electric conductor. Example: The power that runs household appliances.
- Light (Radiant) Energy: A form of electromagnetic radiation that is visible to the human eye. Example: Sunlight or the light from a bulb.
- Nuclear Energy: Energy stored in the nucleus of an atom, released during nuclear fission or fusion. Example: Power generation in a nuclear power plant.
- Sound Energy: Energy that travels in the form of waves through a medium like air or water. Example: The sound from a musical instrument.
3. What is kinetic energy and how is it calculated?
Kinetic energy is the energy an object possesses because of its motion. Any object that is moving has kinetic energy. It depends on both the mass of the object and its velocity. For example, a fast-bowling cricket ball has significant kinetic energy. It is calculated using the formula: KE = ½mv², where 'm' is the mass of the object and 'v' is its velocity.
4. What is potential energy? Explain with an example.
Potential energy is the stored energy an object has due to its position or state. It is energy that has the 'potential' to be converted into other forms, like kinetic energy. A common example is gravitational potential energy. A book held high above the ground has potential energy because of its height in Earth's gravitational field. If released, this potential energy converts into kinetic energy as the book falls.
5. What is the difference between forms of energy and sources of energy?
This is a key distinction. Forms of energy refer to the different ways energy can manifest, such as kinetic, potential, chemical, or electrical energy. Sources of energy are where we derive this energy from. Sources are classified as renewable (e.g., sun, wind, water) and non-renewable (e.g., coal, oil, natural gas). For instance, coal is a non-renewable source that contains chemical energy, which is a form of energy.
6. How is chemical energy stored and released?
Chemical energy is a type of potential energy stored within the chemical bonds that hold atoms together in molecules. This energy is released or absorbed during a chemical reaction when these bonds are broken and new ones are formed. For example, when you burn wood, the chemical energy stored in cellulose is released as heat and light energy.
7. Can one type of energy be converted into another? Explain with a real-world example.
Yes, this is a fundamental principle known as the Law of Conservation of Energy, which states that energy can change from one form to another but cannot be created or destroyed. A perfect real-world example is a hydroelectric dam. The water stored at a height possesses potential energy. When it flows down, this is converted to kinetic energy, which turns turbines (mechanical energy), and the generator then converts this into electrical energy.
8. How does gravitational potential energy differ from elastic potential energy?
Both are forms of stored energy, but they originate from different forces. Gravitational potential energy is stored due to an object's position within a gravitational field, like a ball on a hill. It depends on mass, gravity, and height (PE = mgh). In contrast, elastic potential energy is stored when an object is stretched or compressed, like a drawn bowstring or a compressed spring. It depends on the object's stiffness and the amount it is deformed.
9. Is heat the same as thermal energy? What is the key difference?
While often used interchangeably, in physics they have distinct meanings. Thermal energy is the total internal energy of a system, representing the random kinetic energy of its molecules. Heat, on the other hand, is the transfer of thermal energy from a hotter object to a colder one. So, an object possesses thermal energy, but it transfers heat. Heat is energy in transit, not energy stored.
10. If energy cannot be created, where does all the energy in the universe originally come from?
This is a profound question that touches on cosmology. According to the leading scientific theory, all the energy and matter in the universe were created during the Big Bang. The Law of Conservation of Energy applies to the universe as a closed system after its initial creation. For most practical purposes in physics, like a chemical reaction or a moving object, we consider that the total energy within that system simply transforms from one form to another, rather than being newly created.
