# Chapter 6: Work and Energy

Difficulty Level: At Grade Created by: CK-12

Energy is a common concept in the modern world.  A key to understanding energy in detail is how different kinds of energy transform from one to the other, such as circular motion being changed into electrical power.

Chapter Outline

### Chapter Summary

• Work is defined as , the product of the component of the force along the line of motion and displacement.
• Work has units of N*m, or , also known as Joules (J).
• Energy comes in two forms: kinetic and potential

Kinetic energy is the energy of motion and potential energy is the energy of position. Potential energy can also have many forms. For example: gravitational potential energy, elastic potential energy, chemical potential energy, and nuclear potential energy to name a few.

• Energy is the ability to do work and has units of joules, J.
• Kinetic energy has the form:
• Gravitational potential energy has the form:
• The potential energy stored in a spring has the form:
• The relationship between the applied force and the distance a spring is stretched or compressed is: (Hooke’s Law)
• The Work-Energy principle is
• Dissipative forces such as friction are considered non-conservative forces. Mechanical energy is not conserved in the presence of non-conservative forces.
• The conservation of mechanical energy can be written as:
• In the presence of dissipative forces the conservation of energy can we written as:
• , where is the energy that has been transformed into heat.
• In the event of an explosion, heat, , is added to the initial and energies and in the most general case, heat can also be lost, , after the explosive, thus:
• The average power is the rate at which work is done or consumed or produced : and has units of Watts

Show Hide Details
Description
Difficulty Level:
Authors:
Editors:
Tags:
Subjects:
Date Created:
Jun 27, 2013