Introduction

The Energy Story

  Energy Is Born
  Energy Types
  Energy Changes
  Energy Generation

The Energy Problem

  Conservation of Energy
  Aging of Energy
  Finite Resources
  The Oil "Crisis"
  Energy Pollution
  Discussion Topics

The Energy Solution

  Conserving Electricity
  Appliance Efficiency
  Heating Conservation
  Renewable Energy

Web Links

Teacher Guide

About the Author


Secret Lives Title -  The Energy Story


Energy Changes

As we have said, energy is constantly changing from one type into another. This is happening all around us and throughout the universe.


Examples of Changes
Many of the most obvious examples of energy changing from one type into another occurs in our homes. A number of examples are illustrated below. In each example energy starts as one type (energy in) and changes into another type (energy out). In some cases the energy might actually change into more than one type before the final energy out. In those situations, ignore the energy changes in the middle. Try to identify when this is happening and check your guesses with the information given after the examples.
 
Example Description
Energy In
Energy Out
wok graphic
Electric Wok
Electrical
Heat
flashlight graphic
Flashlight
Chemical
(in the batteries)
Light
guitar graphic
Guitar String
( being plucked)
Mechanical
KE
(sound)
blinds graphics
Blinds
(being opened)
Mechanical
Gravitational
candle graphic
Burning Candle
Chemical
(wax)
Light
hour glass graphic
Sand Clock
Gravitational
Kinetic
crossbow graphic
Arrow Shot From Crossbow
Spring
Kinetic
hand scanner graphic
Hand Scanner
Light
Electrical
toboggan graphic

A Toboggan
Going Downhill

Gravitational
Kinetic
lawn mower graphic
Gasoline Powered Lawnmower
Chemical
Mechanical
microwave oven graphic
Microwave Oven
Light
Heat

Notes: The one example where there was an obvious energy change in the "middle" was the flashlight. Chemical energy from the chemicals inside the batteries first changed into electrical energy before finally being changed into light energy.

Check out the site below for several examples of the changes from kinetic energy (KE) to gravitational energy (PE) and vice versa.

The Physics Classroom The Work-Energy Theorem. See the examples about halfway down the page.