What is Potential Energy? | Definition, Types, Formula & Examples

What is Potential Energy?

Potential energy is the stored energy that an object has due to its position or state. A bicycle on top of a hill, a book high above your head, and a source of stress all have potential energy.

How to Measure Potential Energy

For measuring potential energy the standard unit  is the joule, which is abbreviated as “J.”

How is it different from kinetic energy?

Potential energy is the stored energy while kinetic energy is the energy of motion. When potential energy is used, it is converted into kinetic energy. You can think of potential energy as kinetic energy waiting to happen.

A Car on a Hill

We can compare potential and kinetic energy by considering a car on a hill. When the car is at the top of the hill, it has the greatest potential energy. If it is at rest, it has no kinetic energy. When the car starts to go downhill, it loses potential energy but gains kinetic energy. The potential energy of the car’s position on the top of the hill is converted into kinetic energy.

Gravitational Potential Energy

A kind of potential energy comes from the gravity of the Earth. This is called gravitational potential energy (GPE). Gravitational potential is the energy stored in an object based on its height and mass. To calculate the gravitational potential, we use the following equation:

GPE = mass * g * height
GPE = m*g*h

Where “g” is the standard gravitational acceleration equivalent to 9.8 m/s2. Height is determined based on the height at which the object is likely to fall. The height can be the distance from the floor or it can be the lab table we are working on.

Example problems:

What is the potential energy of a 2 kg stone placed on top of a 10 meter high cliff?

GPE = mass * g * height
GPE = 2kg * 9.8 m/s2 * 10m
GPE = 196 J

Potential Energy and Work

Potential energy is equal to the amount of work done to put an object in its correct position. For example, if you lift a book off the floor and put it on the table. The potential energy of the book on the table will be equal to the work required for the book to move from the floor to the table.

Other Types of Potential Energy

Elastic – Elastic potential is stored when a material is stretched or compressed. Examples of elastic potential energy include springs, rubber bands, and slings.

Electric – Electric field potential is the ability to do work due to an object’s charge.

Nuclear – The potential energy of the particles inside an atom.

Chemical – Chemical potential energy is the energy stored up in substances due to their chemical bonds. An example of this is the energy stored in gasoline for a cars.

Interesting Facts about Potential Energy

Scottish scientist William Rankine coined the term potential energy in the 19th century.

The equation for the potential energy of the spring is PE = 1/2 * k * x2, where k is the spring constant and x is the compression.