All You Need to Know About the Law of Conservation of Energy in Physics

Credit: Richard Bartz/Wikimedia Commons

By Andrew Bennett

What Is the Law of Conservation of Energy?

There are many different types of energy, such as kinetic, potential, mechanical, and chemical energy. Although the amount of these energies change, the total amount of energy cannot change. This rule is called the law of conservation of energy.

Law of Conservation of Energy Definition

Energy can leave or enter a system. It can transform from one form to another, such as potential energy changing to kinetic energy. However, it cannot disappear into or appear from nowhere. It may be a tough job to track it down, but that energy is somewhere!

Conservation of Energy Equation

This energy conservation equation is always true:

$K_0+U_0+W_{NC}=K+U$

This is read as "kinetic energy initial + potential energy initial + work from non-conservative forces = kinetic energy final plus potential energy final."

The most common "non-conservative forces" that would do work in most problems would be applied forces (like a person pushing or pulling on the object), friction, or air resistance. Most early physics problems will not include those forces at all, in which case, the equation would simplify to:

$K_0+U_0=K+U$

However, it might be written differently depending on the types of energy and forces involved in a particular scenario.

Conservation of Energy Videos

Want to learn more about energy conservation? For an example and a more detailed definition of the law of conservation of energy, check out the video below.

Introductory Video

In this video, you will learn more about some of the different types of energy. You will also learn how to apply this physics law to a system to make predictions about the outcome of a scenario.

AP Physics 1 Energy Videos

Ready for a more in-depth look at energy conservation? Check out this playlist for 20+ AP Physics 1 energy videos.

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