Download Chapter 3.1

Chapter 3.1
Energy exists in different forms
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.
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.
Mechanical Energy

Energy that moves objects

Example
 Energy
used to put a book on a shelf
 Energy used to turn a key
Sound Energy
Sound results from the vibration of particles
in a solid, liquid or gas
 Sound cannot travel through empty space

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
Thermal Energy

Total amount of energy from the movement
of particles in matter

Energy of the motion of atoms and molecules
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
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

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
Chapter 3.2
Energy can change forms but is never lost
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

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
Energy Transfer Examples
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