Potential energy is stored energy. An object has a measurable amount of potential energy depending on where it’s located and how it relates to other objects around it — the energy of position.[1]
An apple on the floor has very little potential energy. Lift it to the top of a skyscraper, and suddenly it has a lot of potential energy. It can fall to the ground under the force of gravity. It can also interact with other objects on its descent, such as striking a flying bird or landing on a car roof and damaging it.
When the apple is descending, its potential energy has become kinetic energy, which is the energy of motion. Kinetic energy is the energy a person or an object has due to its motion — in this example, the falling apple. A parked bike on top of a hill has potential energy, which becomes kinetic energy once you start riding it downhill.
Both of these energies are measured in joules. Energy is never destroyed or lost when changing from potential energy to kinetic energy — it is merely transformed from one energy type to another. This is known as the law of conservation of energy.[2]
The potential energy of an object cannot be transferred to another entity – you cannot suck the potential energy out of the apple atop a skyscraper. Kinetic energy is transferable, as witnessed with the falling apple’s kinetic energy damaging a car or hitting a bird.
What Is the Relationship Between Potential and Kinetic Energy?
Relationship Potential and Kinetic Energy explained | Waterfall energy image
The relationship between potential energy and kinetic energy is that potential energy can transform into kinetic energy.
Potential energy is position relative. In other words, it changes depending on an object’s height or distance and the mass of the object. Kinetic energy changes depending on an object’s speed and its mass.
If we think about a waterfall, some still water at the top of the waterfall has potential energy. It isn’t moving and hasn’t gone over the edge. The water flowing from the waterfall has kinetic energy as it flows.[3]
A pendulum is an excellent example of this relationship. As the pendulum swings ever higher upwards, its potential energy increases until it reaches its optimum at the highest point of the swing. At the top of the arc, the potential energy turns into kinetic energy as it swings back down.[4]
What Are Examples of Potential Energy?
There are two primary types of potential energy: gravitational potential energy and elastic potential energy.
The gravitational force of the Earth causes gravitational potential energy. When a person jumps from a high dive board, they land with much force (and a splash) into the swimming pool below.
The Earth’s gravity uses the diver’s gravitational force (their weight) to produce the kinetic energy (movement) that brings the diver into the pool. At the top of the diving board, we can talk about the diver’s gravitational potential energy.
This is the same for apples on trees, bikes on top of a hill, a roller coaster waiting to descend, and a skydiver in a plane — all examples of the potential to do an amount of work.[5]
Elastic potential energy occurs when you stretch or compress something. A rubber band left on a sideboard has little potential energy. If you pick it up and stretch it, you have increased its potential to do some work.
If you release the rubber band, it may fly across the room or scare the cat. You manipulated the rubber band to increase its potential energy, which was then released as kinetic energy as it traveled (motion) across the room. An archer pulling back a bow and coiling a spring are further examples of potential energy.[6]
