# Work-Energy Principle (Theory)

On this page, we discuss the Work-Energy Principle. The Work-Energy Principle is a nice mathematical rule that comes from Newton’s Second Law. It makes it much more convenient to solve many types of mechanics problems. Also, it provides a nice framework for thinking about dynamic systems.

On this page, we discuss more of the theory. Elsewhere, we work through several problems.

#### Table of Links

- Video: Derivation of the Work-Energy Principle
- Video: Work due to a Constant Force
- Video: Work due to gravity
- Video: Work due to a spring

#### Video: Derivation of the Work-Energy Principle

Here is an 11 and a half minute video on the derivation of the Work-Energy Principle. Please watch it here so that I do not have to derive it in class.

#### Video: Work due to a Constant Force

Problems in which work is performed by a constant force are particularly easy to solve using the Work-Energy Principle. This 12 minute video shows you how to calculate the work and solve such a problem.

#### Video: Work due to Gravity

Being able to calculate the work produced by gravity is important in engineering dynamics. We calculate the integral explicitly here so that you never have to do it again. In the end, we see that work produced by gravity is very easy to express mathematically once we know the result.

#### Video: Work due to a Spring

Similarly, being able to calculate the work produced by a spring is important in engineering dynamics. We calculate the integral explicitly here so that you never have to do it again. In the end, we see that work produced by a spring is very easy to express mathematically once we know the result.