A book sitting on a shelf. A laptop plugged in but turned off. Using a bow and arrow. A trampoline filled with jumping children. What do they all have in common? Each is an example of energy. More specifically, they all demonstrate the concepts of potential and kinetic energy.
In this article, you’ll learn more about energy, the difference between kinetic and potential energy and ways energy presents itself in everyday situations.
What is energy?
Energy, broadly, is the ability to do work.
The law of conservation of energy, also called the first law of thermodynamics, is important in understanding the idea of energy. It states that the amount of energy in the universe is constant. It can’t be destroyed or created; it can only be transferred. We experience these transfers of energy, both large and microscopic, throughout our daily lives.
Two main types of energy exist: potential energy and kinetic energy. Using the bow and arrow example from above, we can better understand how kinetic energy and potential energy work.
What is potential energy?
Potential energy is stored energy related to the position of an object or particle. It has the potential to become another form of energy.
Imagine you’re holding the bow and arrow. When you pull the string of the bow back, you have increased the string’s potential — or stored — energy.
What is kinetic energy?
Kinetic energy is the energy an object has because of its motion.
With the string of your bow pulled back and full of potential energy, you release it. What happens? That potential energy shifts to kinetic energy in the arrow, propelling it through the air.
What is the difference between kinetic and potential energy?
As we’ve seen, potential and kinetic energy are different. Something with potential energy is said to have energy stored. Something with kinetic energy is said to be in motion.
Kinetic energy can be transferred from one body to another (such as through a collision). Meanwhile, potential energy does not have the same ability.
However, some things can possess both potential and kinetic energy. A waterfall, for instance. The height of the water at the top of the waterfall would be an example of potential energy. The movement of the water as it falls would be an example of kinetic energy.
What do potential and kinetic energy have in common?
Potential energy can be converted into kinetic energy. And kinetic energy can be converted into potential energy. (This type of energy transfer is accompanied by the dissipation of some energy as heat.) This is one big thing these types of energy have in common.
Types of potential energy
Several types of potential energy exist, including:
Gravitational potential energy – energy held by an object due to its mass and position in a gravitational field.
Examples include: a yo-yo waiting to be released, ripe fruit until it breaks away from the tree branch
Magnetic potential energy – energy stored in a magnetic object’s magnetic field.
Examples include: a compass, an MRI scanner, electric motors
Electric potential energy – energy stored based on the size of an electric charge and its position in an electric field.
Examples include: a vacuum when turned off, a TV before it’s turned on, a car’s headlights when not in use
Elastic potential energy – energy stored in a stretched or compressed elastic object.
Examples include: a trampoline, a mousetrap, a sponge, a rubber band
Types of kinetic energy
Several types of kinetic energy also exist, including:
Radiant energy – energy that travels in electromagnetic waves and particles through space. We usually experience it as heat.
Examples include: sunshine, an incandescent light bulb, an electric toaster
Thermal energy – similar to radiant energy, but it relies on atoms and molecules to function.
Examples include: boiling water, sunshine, a campfire
Sound energy – energy produced when sound waves move outward from a vibrating object or sound source.
Examples include: voices, animal noises, music
Electrical energy – energy created when electrons flow along a circuit.
Examples include: batteries, lightning, wind turbines
Mechanical energy – energy is the energy associated with the mechanical movement of objects.
Examples include: car in motion, rotating fan, hammering a nail
Conclusion
Have you learned a bit more about potential and kinetic energy, how they are different and examples of each? Now, you can notice endless examples of these two types of energy as you go about your day. Take note of stationary objects that have potential (stored) energy and moving objects that have kinetic energy, and you will see that energy really is everywhere!
For more information on powering your home with an important type of energy — electricity — visit Everything Energy.