Summary: Potential energy is the energy an object stores when it’s stagnant. It is released when the object changes position, state, or arrangement. We provide a range of examples, discuss the three types of potential energy, and explain potential energy’s connection to renewable energy.
The discussion about alternative sources of energy has suddenly taken center stage due to rapidly depleting fossil fuels.
There’s certainly a lot of talk about solar energy and wind energy. But it’s also important to understand how the sources of all the renewables — kinetic and potential energy — operate.
In this article, we’ll focus more on potential energy, including what it means, its different forms, and a few potential energy examples. We’ll also touch on how it’s connected to gravitational energy and the Earth.
What Is Potential Energy?
Potential energy refers to the stored energy within an object that exists as a result of the object’s position, state, or arrangement. It’s one of the two primary forms of energy — the other is kinetic energy.
The stored energy is released when the position, state, or arrangement of the object changes. Very aptly named, you can think of it as the energy that has the “potential” to do some work. For instance, when you compress a spring, it has more potential energy since it can change back to its original form. But as soon as you release it, the potential energy (stored energy) is released.[1]
It was the 19th-century Scottish engineer and physicist William Rankin who first used the term potential energy. Interestingly, the term also has links to the Greek philosopher Aristotle’s concept of potentiality and actuality where he first discussed enérgeia, the source of the modern word “energy.”[2]
What Is the Definition of Potential Energy?
Potential energy is defined as the latent energy in an object at rest.
Imagine a system (we’ll call it XYZ) that comprises three different parts: A, B, and C. The potential energy of XYZ will be directly influenced by the object’s position relative to A, B, and C. This is why we define energy potential as a property of a system (XYZ) instead of referring it to as the individual property of just one body or particle (A, B, or C) that forms a part of this system.
To satisfactorily define potential energy, we also need to mention forces known as conservative forces.
A conservative force is defined as any force whose work is determined only by the final displacement of the object acted upon. The total work done by a conservative force is independent of the path resulting in a given displacement and is equal to zero when the path is a closed loop.
Conservative forces ensure the total amount of work done depends on the initial and final position of the body in space.
How Does Potential Energy Work?
Newton’s law of energy conservation states that the total energy in an isolated system remains constant over time.
Potential energy is when an object has energy stored as a result of its position, making it capable of doing more work. For instance, a stretched rubber band is loaded with potential energy. Similarly, a ball, when held above the ground, has more potential energy than it does after it is released and falls.
When you stretch or compress a rubber band, the kinetic energy, which is what you use to compress or stretch the band, gets converted into potential energy. And when you release the band back to its original shape, the potential energy converts back into kinetic energy.
In other words, the energy of an object gets converted from potential energy to kinetic energy and then back to potential energy again. Moreover, the potential energy is position-relative while the latter is motion-relative, with both representing the current state of energy.
To further explain how types of potential energy are part of the system, let’s continue with the raised ball example.
In this scenario, the system comprises the Earth and the raised ball. The ball’s height and mass determine how much energy it possesses as gravitational potential energy. Gravitational energy is a type of potential energy that increases as an object is raised higher above the ground. Both the Earth and ball will have more potential energy when they are separated further. Hence, the force of gravity between Earth and a ball is dependent on the distance separating them. When these two are separated from each other, additional energy is transferred into the system, which is then stored as gravitational potential energy.
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Where Is Potential Energy Stored?
We’ve established that every object — whether stationary or moving — always has potential energy in some form, since the latter is position-relative.
The potential energy of an object refers to the object’s potential to do something. Let’s take the classic bow and arrow example, a favorite of physics teachers for describing potential energy physics.
As soon as you draw the bow back to shoot the arrow, it contains one form of energy: potential energy. The potential energy in the archer’s arm is converted to the potential energy in the bow’s bent limbs. Similarly, elastic potential energy stored in objects like rubber bands and springs occurs when they are stretched or compressed.
The potential energy of the arrow is relative to both the gravitational force of the Earth and the bow’s position. In fact, this applies to you as well.
Imagine yourself lying on the ground. At this moment, your body has little potential force because you’re near the Earth. But if you were suddenly suspended at a certain height above the ground — say, with bungee cords or in a roller coaster — your potential energy would increase. It is height-relative.
The higher you’re suspended from the surface of the Earth, the greater the potential energy, and the weaker the Earth‘s gravitational force.
Where Does Potential Energy Come From?
source
You can group different forms of energy as potential forms of energy, with each form being associated with a specific kind of force that acts in conjunction with other physical properties of matter. This can include mass, electricity elasticity, temperature, electric charge — you name it.
Any definition of potential energy will include the case of gravitational potential energy, where gravitational forces act on the mass of the object. Similarly, elastic potential energy interacts with the electromagnetic force that acts on the elasticity of a deformed object, such as a stretched rubber band or a compressed spring.
What is Thermal Potential Energy?
When energy is stored in the form of heat, it is called thermal potential energy. Thermal energy is a form of both kinetic and potential energy. It plays a crucial role in natural processes like photosynthesis and wind generation, as well as in technology applications such as solar and wind energy conversion.
Thermal potential energy is related to the movement of particles in a substance, with higher temperatures indicating greater kinetic energy of the particles. Chemical potential energy lives in the bonds between atoms and molecules and is set free during chemical reactions.
For example, imagine a plate is placed on a counter. If you want to lift the plate off the counter, you will have to do some work and use some energy. The chemical energy you obtain from the food you consume (which is stored in the chemicals of your body) gives you the potential energy to lift the plate while you do the work.
Now, if you assume a situation of zero energy loss, the energy supplied to lift the plate from the counter will be the same as the increase in the plate’s gravitational potential energy.
You could also release this potential energy by simply knocking the plate off the counter. As the plate falls, the potential energy gets converted into kinetic energy. And when the plate finally hits the floor, the kinetic energy is converted into heat and sound because of the impact.
How Can Potential Energy Be Found?
Before we discuss how to find or calculate potential energy, you need to understand a few related terms: energy, work, and power.
Energy is the ability of a system or an object to do work. It is available in various forms, ranging from mechanical energy to chemical energy to nuclear energy.
Work is the transfer of energy from one object to another. And since potential energy is converted to kinetic energy, work is also connected to kinetic energy.
Power is the measurement of the energy transferred from one object to another.
The unit Joule is used to measure work and energy, while power is measured in Watts. Wattage is also the measurement of heat generation. Since heat is generated any time energy is transferred, it’s an apt measurement unit.
If you’re wondering why we use the same units to measure energy and work, it’s because the two concepts are the same — work is energy in motion.
So, when you want to find the total energy of any object, you want to know three things related to the object:
- Its potential to do work
- Its potential to create heat
- Its potential to generate power
As a result, you have to find out the sum of the object’s mass, its distance from the Earth, electrical charge, distance from other objects, and internal elastic forces (also known as internal mechanical force).
How Do You Calculate Potential Energy?
Here’s how all of this comes together into a formula:
Potential Energy = mgh
In this equation, m is the mass measured in kilograms, g is the acceleration due to gravity, and h is the height in meters.
You can also use this potential energy calculator to enter the variables, and the system will give you the answer.
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What Are the Three Main Types of Potential Energy?
There are three main types of potential energy: elastic potential energy, gravitational potential energy, and chemical potential energy.
Elastic Potential Energy
Elastic potential energy is stored in objects that can be stretched or compressed. The more an object can stretch, the more elastic potential energy it will have. Objects like rubber bands and springs can store energy as elastic potential energy when they are stretched or compressed.
Gravitational Potential Energy
This form of potential energy is stored in an object that is in a vertical position. The force acting on the object is gravity, which is trying to pull it down toward the ground.
The amount of gravitational potential energy depends on the mass of the object and the weight of the object. The heavier and higher the object is off the ground, the more gravitational potential energy it has.
Chemical Potential Energy
What is stored energy called if it’s stored in the chemical bonds of a substance? Chemical potential energy.
Different chemicals contain a large amount of chemical potential energy, which, when released, transforms some part of the energy into work and the other into heat.
Examples of the Three Types of Potential Energy
We’ve already discussed a few potential energy examples, but to help you understand the concept further, we’ll enumerate some examples with regard to its different forms.
- Mechanical gravitational potential energy: One of the classic potential energy examples is a car parked at the top of a hill, because it has the potential to come down the hill. This potential energy is influenced by the object’s position relative to the bottom of the hill.
- Mechanical elastic potential energy: An archer’s bow with the string pulled back is an example of mechanical elastic potential energy, because the pulled string has stored energy that is released when the archer lets go of the bow.
- Chemical potential energy: When a battery is charged, it stores chemical potential energy and converts it to electrical energy.
- Electrical potential energy: A light that is switched off has an electrical charge that’s waiting to flow through the wires.
- Magnetic potential energy: This is a type of energy stored because of attractive forces between two objects, like a pair of metal spoons or two magnets.
How Do You Measure Potential Energy?
Units of potential energy are called joules (J). Joules are the derived unit of energy. They are equal to the energy transferred to (or work done) on an object when the force of one Newton acts on the object in the same direction as that of the motion of the force through a distance of 1 meter or about 3 feet.
Now that we’ve mentioned Newton, let’s discuss joules with the help of an item nearly synonymous with him: apples.
An apple typically weighs 1 Newton (about 102 grams or 0.22 pounds). When you raise an apple to the height of 1 meter, you perform 1 joule of work on it.
When you lift the apple, the potential energy of the apple changes. At its 1-meter height, the apple will have 1 joule of potential energy. But when you release the apple, the force of gravity will come into play. It will end up performing 1 joule of work as the fruit drops one meter in height.
Larger, heavier objects will be measured with a larger number of joules, signifying more units of potential energy.
Where Else Does Potential Energy Exist?
Potential energy is a common phenomenon in our daily lives. From a book kept on a table to a car parked in a driveway to a switched-off cell phone — everything has potential energy.
Potential energy is a common phenomenon in our daily lives. From a book kept on a table to a car parked in a driveway to a switched-off cell phone — everything has potential energy.
Even renewable sources of energy utilize the concept of kinetic energy and potential energy. While wind power converts the wind’s kinetic energy to mechanical energy before using it to generate electricity, biomass energy uses the stored chemical potential energy in the bonds of atoms and molecules that hold particles together.
Potential Energy in Our Daily Lives
We never lose energy. Instead, energy is constantly converting, either from kinetic energy to potential energy or from potential energy to kinetic energy.
Alternative sources of energy are being created by harnessing this phenomenon. These potential forms of energy hold the promise of changing how we power our world. This will help us sustain our Earth and preserve fossil fuels while reducing pollution.
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