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Potential Energy

Potential energy is the energy that is stored in objects based on their position above the ground.

  • The further an object is off the ground, the more potential energy it possesses.
  • This type of energy does not involve motion.
  • Potential energy is converted into kinetic energy. Once an object starts moving, the potential energy (stored energy) is converted into kinetic energy (the energy of motion).

We will discuss three kinds of potential energy in this lesson:

  • gravitational potential energy
  • elastic potential energy
  • chemical potential energy

Gravitational Potential Energy

A diver standing on the high jump platform has gravitational potential energy. The distance from the platform to the surface will determine the diver's gravitational potential energy. We calculate gravitational potential energy by multiplying mass, acceleration due to gravity and the height together.

The equation for potential energy is:

PE = mgh

In this formula,

  • PE stands for potential energy. Sometimes you will see GPE in the formula, which stands for gravitational potential energy.
  • m equals mass
  • g equals the acceleration of gravity, which you know is 9.8 m/s2
  • h equals height

The unit of measurement is a joule (J), which is kg·m2/s2. We use the joule as the unit of measurement for this type of energy, just like it is used as the measurement for kinetic energy.


Elastic Potential Energy

Elastic potential energy is energy that is stored by compressing or stretching an object.

  • When you sit on your bed, the springs inside the mattress compress.
  • When you put on spandex workout shorts, the material stretches.
  • If you stretch a rubber band and let it go, it will soar across the room.

Let's look at that last example in more detail. While the rubber band is in motion, it has kinetic energy. The energy in the rubber band is due to the elastic potential energy stored in the particles in the stretched rubber band.


Chemical Potential Energy

Chemical potential energy is energy that is stored in atoms and the bonds between them. Some examples of items with chemical potential energy are:

  • foods,
  • gasoline, and
  • batteries

Let's look more closely at the last two examples. When you put batteries in an electronic device, the chemicals inside the batteries provide energy to the device. The stored energy in the batteries allows the device to function. Similarly, putting gasoline in your car allows your motor to run so that you can drive your car.

Before continuing, read the Potential Energy page from The Physics Classroom and complete the first Check Your Understanding question at the bottom of the page.