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Copyright © by Holt, Rinehart and Winston. All rights reserved.
Module M: Chapter 5
Energy and Energy Resources
Section 1: What Is Energy?
Section 2: Energy Conversions
Section 3: Conservation of Energy
Section 4: Energy Resources
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is Energy?
Bellringer
Finish the following phrase:
“Energy is the ability to ____.”
Write your completed phrase in your science journal. We
often use the words energy and power synonymously, but
they have specific meanings. What is the distinction
between energy and power?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is Energy?
Objectives
• Explain the relationship between energy and work.
• Compare kinetic and potential energy.
• Describe the different forms of energy.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is Energy?
Energy and Work: Working Together
• What Is Energy? In science, energy is the ability to do
work.
• Energy Transfer When one object does work on another,
energy is transferred from the first object to the second
object.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is Energy?
Kinetic Energy
• What Is Kinetic Energy? Kinetic energy is the energy of
motion.
• Kinetic Energy Depends on Mass and Speed An
object’s mass affects its kinetic energy, but its speed has an
even greater effect on its kinetic energy than its mass does.
•KE = m x v
2
2
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is Energy?
Potential Energy
• Gravitational Potential Energy When you lift an
object,you do work on it. You use a force that is against the
force of gravity. When you do this, you transfer energy to
the object and give the object gravitational potential energy.
• Calculating Gravitational Potential Energy
Gravitational potential energy equals an object’s weight
multiplied by its height. GPE = weight x height [m x g x h]
• Height Above What? Gravitational potential energy
depends on your point of view. So, height is a measure of
how far an object has to fall.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is Energy?
Mechanical Energy
• What Is Mechanical Energy? Mechanical energy is the
total energy of motion and position of an object.
• Mechanical Energy in a Juggler’s Pin The mechanical
energy of an object remains the same unless it transfers
some of its energy to another object. But even if the
mechanical energy of an object stays the same, the
potential energy or kinetic energy it has can increase or
decrease.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
What Is Energy?
Other Forms of Energy
• Thermal Energy Thermal energy is all of the kinetic
energy due to random motion of the particles that make up
an object. Thermal energy is illustrated on the next slide.
• Chemical Energy Chemical energy is the energy of a
compound that changes as its atoms are rearranged.
• Electrical Energy Electrical energy is the energy of
moving electrons.
End of Slide
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Section 1
Thermal Energy in Water
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Section 1
What Is Energy?
Other Forms of Energy continued
• Sound Energy Sound energy is caused by an object’s
vibrations.
• Light Energy Light energy is produced by the vibrations
of electrically charged particles.
• Nuclear Energy Nuclear energy is the energy that comes
from changes in the nucleus of an atom.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Energy Conversions
Bellringer
What do the following objects have in common: a plant, a
Bunsen burner, a pendulum. Can you think of three more
objects that have the same common link?
Record your guesses in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Energy Conversions
Objectives
• Describe an energy conversion.
• Give examples of energy conversions for the different
forms of energy.
• Explain how energy conversions make energy useful.
• Explain the role of machines in energy conversions.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Energy Conversions
Kinetic Energy and Potential Energy
• Energy Conversions and Skateboarding Look at the
next slide to see energy conversions taking place on a
skateboarding half-pipe. The skateboarder’s potential
energy will become kinetic energy as he speeds down the
side of the half-pipe.
• Elastic Potential Energy The wound-up rubber band in a
toy airplane has a kind of potential energy called elastic
potential energy. When the rubber band is let go, the stored
energy becomes kinetic energy, spins the propeller, and
makes the airplane fly.
End of Slide
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Section 2
Potential Energy and Kinetic Energy
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Section 2
Energy Conversions
Conversions Involving Chemical Energy
• Energy Conversions in Plants As shown on the next
slide, photosynthesis uses light energy to make new
substances that have chemical energy.
• The Process Continues Plants change light energy into
chemical energy. The chemical energy in the food you eat
is changed into another kind of chemical energy that your
body can use. Your body then uses that energy to give you
the kinetic energy that you use in everything you do. It’s an
endless process—energy is always going somewhere!
End of Slide
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Section 2
From Light Energy to Chemical Energy
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Section 2
Energy Conversions
Why Energy Conversions Are Important
• Energy Conversions Are Necessary for Life Energy
conversions are needed for everything we do. Heating our
homes, getting energy from a meal, and many other things
use energy conversions.
• Conversions Involving Electrical Energy You use
electrical energy all of the time. When you listen to the
radio, when you make toast, and when you take a picture
with a camera, you use electrical energy. Electrical energy
can easily be changed into other forms of energy.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Energy Conversions
Energy and Machines
• Machines Can Change Energy Some machines change
the energy put into them into other forms of energy. See
how a bicycle does this on the next slide.
• Machines as Energy Converters Machines help you use
energy by converting it into the form that you need.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 2
Energy Conversions In a Bicycle
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Section 3
Conservation of Energy
Bellringer
Where does the energy come from to make a roller coaster
car move? Where does all the energy go? Explain the
meaning of the sentence, “All of the energy put into a
process still exists somewhere at the end of that process.”
Use the roller coaster example to illustrate your explanation
in your science journal.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
Conservation of Energy
Objectives
• Explain how energy is conserved within a closed system.
• Explain the law of conservation of energy.
• Give examples of how thermal energy is always a result
of energy conversion.
• Explain why perpetual motion is impossible.
End of Slide
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Section 3
Conservation of Energy
Where Does the Energy Go?
• Energy on a Roller Coaster To find out where a roller
coaster’s original potential energy goes, you have to think
about more than just the hills of the roller coaster. Friction
plays a part too. Friction is a force that opposes motion
between two surfaces that are touching. See how friction
plays a part in roller coaster energy conversions on the
next slide.
End of Slide
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Section 3
Energy Conversions in a Roller Coaster
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Section 3
Conservation of Energy
Energy Is Conserved Within a Closed
System
• What Is a Closed System? A closed system is a group of
objects that transfer energy only to each other.
• Law of Conservation of Energy According to the law of
conservation of energy, energy cannot be created or
destroyed.
End of Slide
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Section 3
Conservation of Energy
No Conversion Without Thermal Energy
• Perpetual Motion? No Way! People have sometimes
tried to make a machine that would run forever without any
additional energy. This perpetual motion machine would put
out exactly as much energy as it takes in. But that’s
impossible, because some waste thermal energy always
results from energy conversions.
• Making Conversions Efficient In terms of energy
conversions, energy efficiency is a comparison of the
amount of energy before a conversion with the amount of
useful energy after a conversion.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Energy Resources
Bellringer
Write the names of several different energy resources in
your science journal. Predict which ones are
nonrenewable (a finite supply) and renewable (an endless
supply) resources.
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Section 4
Energy Resources
Objectives
• Name several energy resources.
• Explain how the sun is the source of most energy on
Earth.
• Evaluate the advantages and disadvantages of using
various energy resources.
End of Slide
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Section 4
Energy Resources
Nonrenewable Resources
• Uses of Fossil Fuels Oil and natural gas, shown on the
next slide, as well as coal, are the most common fossil
fuels. All fossil fuels contain stored energy from the sun,
which can be converted into other kinds of energy.
• Electrical Energy from Fossil Fuels One way to
generate electrical energy is to burn fossil fuels.
• Nuclear Energy Another way to generate electrical
energy is to use nuclear energy.
End of Slide
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Section 4
Formation of Fossil Fuels
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Section 4
Energy Resources
Renewable Resources
• Solar Energy Sunlight can be changed into electrical
energy through solar cells, photo-voltaics.
• Energy from Water The sun causes water to evaporate
and fall again as rain that flows through rivers. The
potential energy of water in a reservoir can be changed into
kinetic energy as the water flows through a dam.
• Wind Energy A wind turbine changes the kinetic energy
of the air into electrical energy by turning a generator.
End of Slide
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Section 4
Energy Resources
Renewable Resources continued
• Geothermal Energy Thermal energy caused by the
heating of Earth’s crust is called geothermal energy. Some
geothermal power plants pump water underground next to
hot rock. The water returns to the surface as steam, which
can then turn the turbine of a generator.
• Biomass Plants use and store energy from the sun.
Organic matter, such as plants, wood, and waste, that can
be burned to release energy is called biomass.
End of Slide
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Section 4
Energy Resources
The Two Sides to Energy Resources
• Advantages and Disadvantages All energy resources
have advantages and disadvantages.
• Choosing the Right Energy Resource Energy planning
in all parts of the world requires careful consideration of
energy needs and the availability and responsible use of
resources.
End of Slide
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Chapter 9
Energy and Energy Resources
Concept Map
Use the following terms to complete the concept map on
the next slide: potential energy, position, mechanical
energy, motion, kinetic energy, mass, machines.
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Chapter 9
Concept Map
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 9
Concept Map
Copyright © by Holt, Rinehart and Winston. All rights reserved.