1. Energy exists in different forms
Chapter 3.1
Energy exists in different forms

2. Energy All forms of energy cause changes to occur
Wind causes flag to flutter
Light bulb gets hot and glows
You pick up a tennis racket, change position
Hit tennis ball
The ability to cause a change
Energy takes many different forms and has many different effects.

3. Forms of Energy Scientist classify energy into many forms pg 73
Mechanical Energy
Sound Energy
Chemical Energy
Thermal Energy
Electromagnetic Energy
Nuclear Energy
Each form causes change in a different way.

4. Mechanical Energy Energy that moves objects Example
Energy used to put a book on a shelf
Energy used to turn a key

5. Sound Energy
Sound results from the vibration of particles in a solid, liquid or gas
Sound cannot travel through empty space

6. Chemical Energy
Energy that is stored in the chemical composition of matter
Amount of energy
Depends on types of atoms
Depends on arrangement of atoms
Examples
When wood or gasoline burns chemical energy produces heat
Cells use chemical energy that our bodies store from the food we eat

7. Thermal Energy
Total amount of energy from the movement of particles in matter
Energy of the motion of atoms and molecules

8. Electromagnetic Energy
Energy transmitted through space in the form of electromagnetic waves
Can travel through empty space
These waves include
Visible light
X-rays
Microwaves
Sun releases large amount that is absorbed by Earth

9. Nuclear Energy
The center of an atom, its nucleus, is the source of nuclear energy
When a heavy atoms nucleus breaks apart energy is released
When the nuclei of two small atoms join together energy is released

10. General Types of Energy
All forms of energy can be described in terms of two general types of energy
Kinetic Energy – energy of motion
Increases as mass increases
Increases as speed increases
Potential Energy – stored energy
Due to position (pg 76)
Gravity, stretching, compressing
chemical composition
Energy stored in food, fuel in rocket engine
Potential and Kinetic Energy demonstration

11. Energy can change forms but is never lost
Chapter 3.2
Energy can change forms but is never lost

12. Energy Changes Form How does energy change form?
Example – a match
PE is stored in the chemicals on the head of the match
The flame releases that energy as light and heat
Conversions between PE and KE
Examples – roller coaster, ski jumper, skate boarder
Using Energy Conversions
Water stored behind a dam is changed to electrical energy
Pg 80 for other examples

13. Law of Conservation of Energy
States that energy can neither be created nor destroyed.
It may appear that energy is lost or gained
It only changed form Example 2nd example
Useful energy is always less than the total amount of energy
Energy conversions may produce unwanted forms of energy
Electrical energy may be converted into unwanted sound energy – (ie) a fan

14. Energy Transfer Examples

15. Energy Efficiency
Measurement of usable energy after an energy conversion
High efficiency
Converts greater percentage of energy into the desired form
Low efficiency
Converts a greater percentage of energy into an inefficient form