An Introduction to Potential Energy | Learning Resource

An Introduction to Potential Energy

by | Educational, Energy

Energy not only makes the world go round (literally), but it’s also the fundamental basis for all processes in the universe. Every movement, every reaction — everything — gives or receives energy[1].  

Like matter, which is simply energy in a different form, energy cannot be created or destroyed. And held within matter, including every person and thing on Earth, is a form of energy that is ready to change form and act on other objects in the vicinity and possibly beyond. This is potential energy, one of the most important processes in the known universe. 

What Is Potential Energy? 

Potential energy is an essential form of energy and is one of the two main types with the other being kinetic energy. The term “potential energy” was first coined by Scottish physicist William Rankine in the 19th century, and it has been a pillar of physics ever since.[2] This form of energy is stored in objects, which hold the potential to release this energy due to the position they are in, making them position relative.  

This is best demonstrated in an object like a slingshot, which stores the energy that is created from pulling back the elastic. The potential energy stored in the pullback is responsible for the energy that occurs upon release, which is known as kinetic energy. However, potential energy is not only stored in elastic objects. Anything that is suspended above the ground or along an incline has the ability to store potential energy[3].  

When objects are displaced from positions of equilibrium, they gain energy — which can happen from letting go of the slingshot or from the force of gravity pulling the object towards Earth. The energy gained comes from the potential energy that was stored in the objects before being knocked out of equilibrium by elastic rebound or gravity[4]. This is due to the conservation of energy[5] 

What Is the Definition of Potential Energy? 

Definition for Potential Energy | Defining Potential vs Kinetic Imagesource

Energy is the ability to do work, which is when a force is applied to an object and it moves[6]. 

Potential energy is essentially stored energy that has the ability to do work because of the position or state of the object in question[7].  

In more physics-focused terms, potential energy is defined as energy stored in a system of forcefully interacting physical entities[8]. These “physical entities” are better classified as “objects” — from tiny particles to large components of the solar system. They contain stored energy, which is transferred into motion.  

Kinetic energy, which is the form of energy that is created when potential energy is released, is the energy of motion. All objects in motion are releasing kinetic energy[9], which is always created by the release of potential energy stored while stationary — and spurred into motion by gravity or elastic forces. 

What Does Potential Energy Mean? 

The meaning of potential energy is fairly straightforward: It is a form of energy that has the potential to do work but is not actively doing work or applying any force on any other objects[10]. In other words, potential energy is about the position of objects, not their motion.  

The concept of potential energy is sometimes difficult to grasp as energy is often thought of in terms of movement. Understanding kinetic energy is intuitively easier because it’s more apparent that moving things have energy. Getting hit by a ball that has been thrown or being struck by a moving vehicle can make someone feel the energy that those objects are carrying. But understanding that there is a form of energy held within stationary objects, where it is locked away and stored until it is knocked out of equilibrium, is a bit trickier.  

According to Educalingo’s definition of potential energy, it is a form of energy that is “associated with forces that act on a body in a way that depends only on the body’s position in space.”[11]  

Where Is Potential Energy Stored? 

Potential energy is technically stored within matter, though a force must be applied to an object in order for it to store potential energy[12]. However, while the energy itself is stored in the mass of the object, another force (gravitational or elastic) must be present to release the potential energy[13]. 

Think of an object like a bowling ball that is raised to the top of a five-meter tower before a free fall. The height against gravity determines the amount of potential energy stored in this object. However, the energy itself is still stored within the object.[14] In this case, the Earth’s gravity is needed to help create the stored energy, but it cannot be stored within the gravitational force itself.  

The same is true for a slingshot: The potential energy is stored in the object being flung rather than the elastic band. The mass of the object is needed to create the tension in the band, which fills with potential energy as it’s pulled. Once released, the potential energy in the object releases and converts to kinetic energy in an energy transfer — the elastic is merely the force that created the transition of energy, just like gravity in the bowling ball example.  

Where Does Potential Energy Come From? 

Potential energy comes from matter — it is an inherent property of anything with mass[15]. But a force is needed, either elastic or gravitational, to instill potential energy within the matter[16]. Without forces, potential energy would not exist. 

The potential energy is stored within any object that is then subjected to an unbalancing of its equilibrium. When this equilibrium is upset, potential energy, which comes from forces that set the object in a stationary balance, is converted to kinetic energy, or energy in motion[17]. The potential energy is transferred to the object or process that is moving or giving the kinetic energy. 

How To Find the Potential Energy of a System? 

There are several equations to find the amount of energy an object has. Perhaps the most famous equation of all time, E=MC², is a formula for finding the energy of an object by multiplying its mass by the square of the acceleration of gravity[18]. However, this is applicable only for kinetic energy.  

To find the potential energy of an object due to gravity, the equation looks like this: Ep=mgh (Potential energy = mass × gravity × height).[19] All that is needed is the weight (mass) of the object and a measurement of how high it’s located off the ground to find the potential energy of the object — simply multiply the weight by the gravitational constant of 9.8 m/s2 and then by the height of the object’s location as a reference point[20] 

What Is an Example of Potential Energy? 

Given that potential energy permeates every aspect of everyday life on a daily basis, there are countless examples of it. 

A sled at the top of a snowy hill has potential energy. So does a propeller on a toy airplane that has been wound up by an elastic band. Tree branches along the canopy in a forest all have potential energy and can fall whenever the equilibrium of forces holding them up becomes unbalanced. The same is true for stones sitting on a cliff edge, statues sitting on a building ledge, and wooden signs hung above doorways. Potential energy is literally everywhere. 

What Are the Types of Potential Energy? 

Types of Potential Energy | Examples - Slingshot imagesource

While potential energy itself is one of the two main forms of energy, along with kinetic energy, there are different forms that it can still take[21]. These forms are gravitational potential energy and elastic potential energy.  

There is also another form of potential energy known as chemical potential energy and electric potential energy[22].  But these are very different from the other main forms as they rely on electric charges within electric fields to move electrons through a force field or magnetic field to act on objects. 

Gravitational Potential Energy 

Gravitational potential energy is stored within an object as it is raised to a higher level or increased height within the gravitational field[23]. This is the type of potential energy that is present in the bowling ball on a tower ledge.  

Elastic Potential Energy  

Elastic potential energy is the total energy stored in objects that can be stretched or otherwise compressed[24]. This is the type of energy present in the slingshot example, as well as with rubber bands, Olympic trampolines, and Medieval catapults, among other objects.  

What Is Potential Energy Measured In? 

All forms of energy, including kinetic and potential energy, are measured in kg*m2/s2, which can be written as a more standard unit known as Joule (J)[25]. The Joule is the standard scientific unit for measuring both work and energy since energy and work measure the same type of force.  

One Joule is equal to the amount of work done by a force of one Newton (N) on an object that moves one meter in the direction of the force being applied[26]. It is equivalent to one 3600th of a watt-hour, or one kg*m2/s2. This applies to mechanical energy as well.  

Potential Energy In a Nutshell 

Energy permeates all areas of life on a daily basis. Although kinetic energy is more visible and easier to understand, potential energy is just as present. It is apparent with every object that rests on a ledge or every time an elastic tie is pulled back with tension.  

Equations can be used to find the exact measurement of potential energy in Joules, but approximate measurements can be seen or felt whenever a ball rolls down an inclined plane or an arrow is released from an archer’s bow.  

Whenever an object is at rest, remember: it is full of potential energy just waiting to be released. 

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Sources:

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