Download Document

LESSON
2
Energy Transformations
LESSON INTRODUCTION
Get Ready
What do you think?
Before you begin, decide if you agree or disagree
with each of these statements.
As you view this presentation, see if you change
your mind about any of the statements.
LESSON
2
Energy Transformations
LESSON INTRODUCTION
Get Ready
Do you agree or disagree?
•
Energy can change from one form to another.
•
If you toss a baton straight up, total energy
decreases as the baton rises.
LESSON
2
Energy Transformations
LESSON INTRODUCTION
Key Concepts/Essential Questions
• What is the law of conservation of energy?
• How does friction affect energy
transformations?
• How are different types of energy used?
LESSON
2
Energy Transformations
Vocabulary
Watch out for these words!
• law of conservation of energy
• friction
LESSON INTRODUCTION
LESSON
2
Energy Transformations
LESSON INTRODUCTION
What’s the sound?
Look at the photo at the beginning of the
lesson. Blocks of ice breaking off the front of
this glacier can be bigger than a car. Imagine
the loud rumble they make as they crash into
the sea. But after the ice falls into the sea, it
will gradually melt. All of these processes
involve energy transformations—energy
changing from one form to another.
Energy Transformations
Ch-5 Lesson 2
LESSON
2
The Law of Conservation of Energy
• States that the total amount of energy in
the universe stays the same.
• Energy cannot be created.
• Energy cannot be destroyed.
• Energy can move from one object to
another (energy transfer).
• Energy can change form (energy
transformation).
LESSON
2
Energy Transformation Example
• A ball is tossed up in the air and then comes back down.
LESSON
2
More Examples
A person eats spaghetti and later goes for a walk.
Chemical potential energy  kinetic energy
Uranium is used to power a nuclear power plant.
Nuclear energy  electrical energy
A person listens to a CD player.
Electrical energy  mechanical energy  sound energy
Water flows over a water fall.
Kinetic and potential energy  kinetic energy and sound
energy
A microwave oven is used to pop popcorn.
Electric energy radiant energy thermal energy  sound
energy
LESSON
2
Pendulums Transform Energy
LESSON
2
Friction and The Law of Conservation
of Energy
• What happened to the pendulum’s mechanical
energy when it stopped swinging?
• The mechanical energy of the
pendulum is not destroyed. Instead, it
changes form. It changes into thermal
energy.
• Friction between surfaces always
changes mechanical energy into
thermal energy.
LESSON
2
Waste Energy
• Whenever energy changes form,
some thermal energy is always
released. Sometimes it is useful,
sometimes it is not.
• Thermal energy that cannot be used
is called waste energy.
LESSON
2
Energy Transformations
LESSON WRAP-UP
Lesson Review
Do you agree or disagree?
Energy can change from one form to another.
Agree. When energy is used, it is usually changed
from one form to another.
LESSON
2
Energy Transformations
LESSON WRAP-UP
Lesson Review
Do you agree or disagree?
If you toss a baton straight up, total energy
decreases as the baton rises.
Disagree. If you toss a baton straight up, total
energy does not change as the baton rises.
LESSON
2
Energy Transformations
LESSON WRAP-UP
Key Concept/Essential Question Review
What is the law of conservation of energy?
According to the law of conservation of energy,
energy can be transformed from one form into
another or transferred from one region to another,
but energy cannot be created or destroyed.
LESSON
2
Energy Transformations
LESSON WRAP-UP
Key Concept/Essential Question Review
How does friction affect energy transformations?
Friction transforms mechanical energy into thermal
energy.
LESSON
2
Energy Transformations
LESSON WRAP-UP
Key Concept/Essential Question Review
How are different types of energy used?
Different types of energy are used by transforming
it from one form to another.