introduction to energy...of energy from a certain amount of oil, but use 8 units of energy to...

Introduction to

Energy

Unit Study for Grades K - 6

© Jenny Phillipsii

INTRODUCTION TO

Created by Mindi Eldredge

Table of ContentsUnit Informa on iii

Supplies Needed iv

Op onal Read-Aloud Story Books v

Lesson 1 - What Is Energy? 1

Lesson 2 - Atoms, Molecules, and Forms of Energy 7

Lesson 3 - Forms of Energy: Experiments 22

Lesson 4 - The Transfer of Energy 25

Lesson 5 - Poten al and Kine c Energy 31

Lesson 6 - Renewable and Non-Renewable Energy 39

Grades 7-12 Unit Extension 49

Energy

EnergyINTRODUCTION TO

©2016 Jenny Phillips | www.Jennyphillips .com

No part of this PDF document may be copied or distributed for those outside your family or school group.

Science JournalAll of The Good & the Beau ful science units include ac vi es for a science journal. For each child, prepare a 1” to 2” 3-ring binder to func on as their “science journal.” Have wide-ruled paper and blank white paper on hand for science journal ac vi es. All completed journal ac vi es are to be kept in the science binder. You may also consider having children create a cover for their science journals, which they insert under the clear cover of the binder.

Science WallAll of The Good & the Beau ful science units include vocabulary words to be placed on your “science wall,” which is a wall in your learning area on which you can a ach the vocabulary words and other images. Print and cut out the vocabulary word cards at the beginning of the unit. The course will indicate when to place them on the wall.

Lesson Mini BooksMany lessons include science mini books. To make your mini books, simply print the

pages single-sided, cut them in half along the do ed lines, stack the pages together, and staple twice along the le side.

Lesson Prepara onAll of The Good & the Beau ful science units include easy-to-follow lesson prepara on direc ons at the beginning of each lesson.

ExperimentsMany of The Good & the Beau ful science lessons involve hands-on experiments and teacher demonstra ons. Always supervise children as they par cipate in the experiments to ensure that they are following all necessary safety procedures.

Teaching Older Children?This unit study is designed for Grades K-6. If you are also teaching older children (Grades 7-12), look for the “older children” symbol at the end of some of the lessons in this unit. There you will fi nd ideas for guiding older children through more in-depth research and study.

Addi onally, you will fi nd at the end of the unit an 18-page ar cle tled “Energy” wri en for older children (Grades 7-12).

Unit InformationThis unit is wri en as an introduc on to and overview of energy subjects. It is suggested as a prerequisite to the physics

units in The Good & the Beau ful curriculum including Heat, Light, and Sound; Gravity, Forces, Mo on, and Simple Machines; Electricity and Magne sm.


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Lesson 1 - What Is Energy?• One small toy car• One ball (any size)• One candle (any size)• Matches or lighter• Op onal read-aloud books (see read-aloud page)

Lesson 2 - Atoms, Molecules, and Forms of Energy• Three containers of diff erent colored play-dough per

child• One dozen toothpicks per child• Op onal read-aloud books (see read-aloud page)

Lesson 3 - Forms of Energy: Experiments• One plas c spoon• Two plas c cups• One piece of yarn at least three yards long• One sandwich-sized plas c bag per child• 1/3 cup vinegar per child• A couple drops of food coloring per child• Two tablespoons of baking soda per child• A digital camera or a phone with a camera• One rubber band per child• A hot glue gun and glue s ck• One small plas c toy animal• One paper plate• Two cra magnets, 3/4 inch diameter• 15 graham crackers• 3/4 cup margarine• 1/2 cup powdered sugar• 1 cup chocolate chips• 12 large marshmallows• One muffi n n• 12 muffi n cup liners• One medium-sized bowl

Lesson 4 - The Transfer of Energy• One ba ery powered fl ashlight• Two balls, one smaller than the other (for best results

use one ball roughly the size of a ping-pong ball and one ball between the size of a cantaloupe and basket-ball)

• One set of dominoes or domino-shaped blocks• One water bo le with lid• One piece of yarn several feet long• Tape (op onal)• One long pole, such as a broom handle (op onal)• Op onal read-aloud books (see read-aloud page)

Lesson 5 - Poten al and Kine c Energy• One 8.5”x8.5” piece of construc on paper per child• Nine cra s cks or popsicle s cks per child• Six regular size rubber bands per child• One plas c spoon per child• Three cra magnets, 3/4 inch diameter (op onal)• One hot glue gun and glue s ck (op onal)• One ruler or wooden paint s r s ck that a magnet can

be glued to (op onal)• One piece of thread several feet long (op onal)• Tape (op onal)• A stack of books (op onal)• Op onal read-aloud books (see read-aloud page)

Lesson 6 - Renewable and Non-Renewable Energy• One die• One game pawn per child (other games’ pawns or

items such as colored rocks or bu ons may be used)

Supplies Needed


EnergyINTRODUCTION TO

© Jenny Phillipsvi

Energythe ability that God gave to all things to

perform work

Vocabulary - Energy

Instructions: Cut out the boxes on this page and place them on your “science wall” as you discuss the vocabulary words. Review the vocabulary words each day during this unit and at various times throughout the year.

The Law of Conservation of EnergyEnergy is never created or destroyed but can be

transferred and transformed.

Transferto move from one object to another

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Atomsextremely small particles that are the building blocks

of all substances upon the earth

Moleculemore than one atom bonded together

Molecule

Atom

Atom

ElectronNucleus

Protons and Neutrons)

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Science

Prepara on

For each child, print one copy of the “Build an Atom” page included in this lesson.

Print and cut out one copy of the “Forms of Energy Title Cards,” “Forms of Energy Defi ni on Cards,” and “Examples of Energy Cards.”

Op onal Read-AloudAt any point in the lesson, you may wish to read one or more of the children’s books listed in the read-aloud sec on at the

beginning of the unit.

Read to children:

Not all energy is the same. There are many diff erent forms of energy on the earth and throughout the universe. Today we are going to talk about some of the main forms of energy. However, before we talk about forms of energy, we need to understand more about what makes up the substances on the earth.

Extremely small particles that make up all substances on the earth are called atoms. Atoms are so small that they can only be seen using special high-powered electron microscopes. Atoms are like tiny building blocks that, when put together, make larger items. For example, your body is made of atoms. The chair you sit on is made of atoms. The table is made of atoms. The food you eat is made of atoms. Even the air you breathe is made of atoms.

Atoms are made of protons, neutrons, and electrons. And every single atom contains energy.

Ac vity

Give each child a “Build an Atom” page and three containers of play-dough, each a diff erent color. Show children the Atoms vocabulary card and tell children they will be making their own model of an atom.

1. Have children choose one color of play-dough and roll three to four marble-sized balls with it. Have children place them on the center of their

“Build an Atom” paper.

2. Have children choose a second color of play-dough and make another three to four mar-ble-sized balls. Have them place these with the others on the center of their pages and gently

Objec ve

• Help children iden fy many diff erent forms of energy.• Understand vocabulary words: atoms, molecule, mechanical energy, electrical energy, light energy, heat

energy, sound energy, chemical energy, nuclear energy, magne c energy.

Lesson 2

Lesson 2 - Atoms, Molecules, and Forms of Energy

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Science Lesson 2

press them together so that they are s ll sepa-rated by color but all grouped together into one ball.

3. Tell children that this represents the nucleus or center of an atom. The nucleus of an atom is made up of protons and neutrons.

4. Have children take the third color of play-dough and roll out three to four pea-sized balls. Have children place the balls in diff erent spots on the three outside rings of their “Build an Atom” page.

5. Tell children that these represent electrons. Elec-trons are the part of the atom that spin around the outside of the nucleus.

6. Reiterate to children that, although the model of the atom they created is large, atoms are actually extremely small.

7. Have children take all the play-dough balls on the “Build an Atom” page and gently press them together into one ball.

8. Explain that though we have spread out the parts of an atom on the “Build an Atom” page, the parts of the atom are held all together crea ng one li le atom. Tell children that the ball containing the protons, neutrons, and electrons will represent one atom throughout the remainder of the lesson.

9. Leave the play-dough atom and the “Build an Atom” page out for use later in the lesson.

Science Wall

Place the vocabulary card Atoms on the science wall.

Read to children:

When an atom joins with one or more other atoms, they become bonded together and create a molecule. Molecules are made up of different types of atoms. The specific types of atoms, the number of atoms, and the arrangement of atoms in each molecule determines the type of molecule. For example, when two hydrogen atoms join together with one oxygen atom, they form a water molecule.

Ac vity

Have children build a molecule using tooth picks and play-dough.

1. Show children the Molecule vocabulary card. Tell children they will place atoms together to create a model of a molecule.

2. Have children create four more atom models using the “Build an Atom” page as a guide.

3. Have children s ck the end of a toothpick into one “atom” ball of play-dough.

4. Have children take another play-dough ball and place it at the other end of the tooth pick.

5. Have children take another toothpick and s ck it into the other side of one of the balls. Have them then s ck another ball at the other end of that toothpick.

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Science Lesson 2

6. Children will con nue un l they have a model of a molecule.

7. Explain to children that each individual ball represents an atom, but that when the atoms are bonded together, the whole group of bonded atoms represent a molecule.

8. Point out that, although molecules are larger than single atoms, they are s ll extremely small--smaller than the naked eye can see.

9. If me allows, children may build more molecules, arranging each diff erently.

Science Wall

Place the vocabulary card Molecule on the science wall.

Read to children:

Now that we understand what atoms and molecules are, we can discuss eight common forms of energy.

Ac vity

Lay the “Forms of Energy Title Cards” across a table or fl oor. Also, lay out the “Examples of Energy Cards” in random order. Tell children that they will match up the tles, defi ni ons, and examples of diff erent forms of energy.

Fan out the “Forms of Energy Defi ni on Cards.” Have children take turns choosing a defi ni on card,

reading it aloud, and deciding with the group what type of energy they think it defi nes. Then, have the group choose which example cards best fi t the specifi c form of energy.

Con nue un l all of the cards have been matched up.

Answers:

[Mechanical Energy: This form of energy comes from the motion of an object or the possible motion of an object because of its location. Mechanical energy example cards: “Cutting With Scissors,” “A Falling Ball,” “A Moving Bike”]

[Electrical Energy: This form of energy is created when electrons move rapidly from atom to atom. Electrical energy example cards: “An Ipod Charging,”

“Lightning,” “Power Lines”]

[Light Energy: We see this form of energy when electromagnetic waves move through space or air. This energy allows us to see all that is around us. Light energy example cards: “Sunshine,” “A Flashlight Turned On,” “A Light Bulb Turned On”]

[Heat Energy: This form of energy is created as molecules move about within a substance. The faster the molecules move, the hotter the substance becomes. The slower the molecules move, the cooler the substance is. Heat Energy example cards: “A Volcanic Eruption,” “A Stove Turned On,” “Fire in a Barbecue”]

[Sound Energy: This form of energy comes from the vibration of an item. The vibration sends out special waves that we can hear. Sound energy example cards: “Music From a Saxophone,” “A Ringing Alarm Clock, “Music Playing on Headphones”]

[Chemical Energy: This form of energy is released when the bonds of molecules are broken apart. The released energy can be used as fuel for humans, animals, cars, and more. Chemical energy example cards: “Digesting a Hamburger,” “Energy Within a Battery,” “Gasoline”]

[Nuclear Energy: This form of energy is released when the center of an atom, the nucleus, is split or when an atom’s nucleus is joined with the nucleus of another atom. Nuclear energy example cards:

“Nuclear Fission Reactions at a Power Plant,” “Nucle-ar Fusion: The Combining of Two Nuclei,” “Nuclear Fission: The Nucleus of an Atom Splitting”]

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Lesson 2Science

[Magne c Energy: In most atoms, the electrons spin randomly around the nucleus. However, in some types of atoms, the electrons all move in the same direction. When these types of atoms line up together, they create magnetic energy. Magnetic energy example cards: “A Compass,” “A Magnet,” “Earth’s Magnetic Field”]

Science WallIf space allows, place the forms of energy tles,

defi ni ons, and example cards on the science wall.

Older Children - Lesson ExtensionHave older children (Grades 7-12) read sec on

one through fi ve of the “Grades 7-12 Unit Extension: Energy” reading material found at the end of this unit. A er reading, have

children write a one page descrip on of what energy is, what the Law of Conserva on of Energy is, and how energy aff ects their everyday lives.

Note: This lesson includes a photo by IgniX - Own work, CC BY-SA 3.0, h ps://commons.wikimedia.org/w/index.php?cu-rid=11238866.

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Lesson 2

Build An Atom

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Mechanical Energy

Electrical Energy

Light Energy

Heat Energy

Forms of Energy Title Cards

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Nuclear Energy

Chemical Energy

Sound Energy

Forms of Energy Title Cards

Magnetic Energy

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This form of energy comes from the motion of an object or the possible motion

of an object because of its location.

Forms of Energy Definition Cards

This form of energy is created when electrons move rapidly from atom to atom.

We see this form of energy when electromagnetic waves move through

space or air. This energy allows us to see all that is around us.

This form of energy is created as molecules move about within a substance. The faster the molecules move, the hotter

the substance becomes. The slower the molecules move, the cooler the substance is.

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This form of energy comes from the vibration of an item. The vibration sends

out special waves that we can hear.

This form of energy is released when the bonds of molecules are broken apart. The released energy can be used as fuel for

humans, animals, cars, and more.

This form of energy is released when the center of an atom, the nucleus, is split, or when an atom’s nucleus is joined with the

nucleus of another atom.

Forms of Energy Definition Cards

In most atoms, the electrons spin randomly around the nucleus. However, in some types of atoms, the electrons all move in the same direction. When

these types of atoms line up together, they create magnetic energy.

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Examples of Energy Cards

Digesting a HamburgerSunshine

A Volcanic EruptionMusic from a Saxophone

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Cutting with Scissors

A Flashlight Turned On

Energy within a Battery

An iPod Charging

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Gasoline

LightningA Falling Ball

A Moving Bike

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Power LinesA Light Bulb Turned On

Fire in a BarbecueA Stove Turned On

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Nuclear Fission Reactions at a Power Plant

A Ringing Alarm Clock Music Playing on Headphones

Nuclear Fusion: The Combining of Two Nuclei

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A Compass A Magnet

Nuclear Fission: The Nucleus of an Atom Splitting Earth’s Magnetic Field


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Science

Read to children:In our last lesson we learned about diff erent forms of energy. We discussed mechanical, electrical, light, heat, sound, chemical, nuclear, and magne c forms of energy. Today we are going to par cipate in experiments and ac vi es involving all of these forms of energy (except nuclear energy). Let’s review each of these forms of energy. Briefl y review the defi ni ons of the eight forms of energy discussed in Lesson 2.

Science Journal

Have children take a piece of blank paper from their science journals and label the top of the paper “Forms of Energy.” Have children

draw lines dividing the page into six even rectangles. Have them label the top of each of the boxes with the following tles: “Mechanical Energy,” “Electrical Energy,” “Light Energy,” “Heat Energy,” “Sound Ener-gy,” and “Chemical Energy.” As children observe and/or par cipate in the following experiments, have them iden fy which form of energy was observed: mechanical, electrical, light, heat, sound, or chemi-cal energy. Children will then draw a picture of the experiment in the applicable space on their paper. Have the children place the page in their science journals.

Experiment #1Bending Water: Electrical EnergyTurn a sink on slowly so that a very small stream of water comes out. Place the rounded

part of the spoon next to the stream of water, showing the children that nothing happens. Then, rub the rounded part of the spoon back and forth briskly through your hair. Now place the rounded part of the spoon next to the stream of water and watch as the water bends slightly towards the spoon.

Without telling them which type of energy was shown, explain to the children what they observed in this experiment. As the spoon was rubbed rapidly through the hair, the electrons from the atoms of the hair moved to the atoms of the spoon. The addi on-al electrons on the spoon give the spoon a nega ve charge. The stream of water coming from the sink has posi vely charged atoms. Opposite charges a ract, causing the posi ve charge in the stream of water to be drawn to the nega ve charge in the spoon.

Lesson 3

Prepara on

Print one copy of the “Oven Cupcake S’mores” recipe.

Objec ve

• Children will par cipate in energy experiments and iden fy the forms of energy exhibited.

Lesson 3 - Forms of Energy: Experiments

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Science

Prepara on

Print and assemble one copy of the Transferred and Converted mini book included in this lesson.



Read to children:God organized energy in a way that it is never created or destroyed. Instead, energy is always present. It may be transferred from one object to another and change form, but it is always there. Today we are going to learn more about the transfer of energy.

Lesson Mini BookRead to the children the mini book included in this lesson: Transferred and Converted.

Science WallPlace the vocabulary cards The Law of Conserva on of Energy, transfer, and convert on the science wall.

Read to children:This fl ashlight is an example of light energy. Turn on a ba ery powered fl ashlight. If energy is never created

or destroyed, where did this light energy come from? Pause for response. The ba ery inside this fl ashlight is full of chemical energy. When I push the bu on a mechanism inside the fl ashlight allows the ba ery to transfer some of its energy through the fl ashlight. As the chemical energy is transferred from inside the ba ery to the fl ashlight, the energy is converted into electrical energy and sent to the bulb at the end of the fl ashlight. Special material inside the bulb lights up when electricity fl ows through it. Thus, the electrical energy changes to light energy. This example shows us the transfer of energy from the ba ery to the light bulb.

Now we are going to try three experiments that demonstrate the transfer of energy. As we complete these experiments, no ce where the transfers of energy take place.

Experiment #1Have children each take a turn trying the following experiment:

Objec ve

• Help children understand that the transfer of energy is energy changing forms or being transferred to another object.

• Defi ne vocabulary terms: The Law of Conserva on of Energy, transfer, convert.

Lesson 4

Lesson 4 - The Transfer of Energy

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Science Lesson 4

Take two balls, one smaller than the other. (For more drama c results use one ball roughly the size of a ping-pong ball and one ball at least the size of a cantaloupe or as large as a basketball.) Drop the larger ball and note how high the ball bounces. Then drop the smaller ball and note how high it bounces. Now take the two balls together, place the smaller one on top of the larger one and drop them together. Watch as they land. The bo om ball does not bounce as high as it did before but it transfers its energy to the top ball.

Ask the children to describe the energy transfer that they observe.

Experiment #2Have children build a domino trail around the room. To set this up, have them stand each domino on end about an inch apart.

A er the dominoes are set up, have them p the fi rst domino towards the second domino to start a chain reac on.

A er the experiment is complete, discuss with children what items they observed the transfer of en-ergy in. Make sure to point out the energy that came from the person who fi rst pushed the domino over.

Experiment #3Have children build and experiment with a pendulum to show the transfer of energy. Two op ons for building the pendulum are shown

below. Choose the pendulum that will work best with the items you have on hand. A er children set up the pendulum, have them build a tower using items such as blocks or paper cups. Have children swing the pendulum to knock over the tower. Discuss with children the transfer of energy that they observe.

Pendulum 1:

Place a long pole, such as a broom handle, between the slats of two chairs. Tie a piece of yarn around the neck of a full bo le of water. Tie the yarn to the pole so the bo le hangs at least an inch above the fl oor.

Pendulum 2:

Tie a piece of yarn around the neck of an empty soda or water bo le. Tape the other end of the yarn to a counter or table top so the bo le hangs at least an inch above the fl oor.

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2

This is called The Law of Conserva on of Energy.

Transferred and Converted

Energy is ever present in the world around us. That energy is never created nor destroyed but is eternal. O en energy changes form as it is transferred from one item to another, but none of the energy is destroyed along the way.

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4

O en when energy is transferred from object to object, the energy changes form. When energy changes form, we say it is converted.

Energy can be converted from electrical energy to light energy, from chemical energy to mechanical energy, from mechanical energy to

sound energy, and in many other ways.

3

Let’s pretend you are bowling. As you bowl, energy is transferred mul ple mes. To begin with, the energy in the food you’ve eaten provides your

body with the strength to walk and to roll the bowling ball. The energy in your body is transferred to the bowling ball. And when the bowling ball hits the pins, the energy in the bowling ball is transferred to the pins.

Electricity is transferred from the wall outlet to the night light.

When the electrical energy reaches the light bulb, it is converted to light energy.

We know that energy can be transferred and changed in form. But what does transfer actually mean? To transfer something means to move it from one object to another. So when energy is transferred, it moves from one object to another.

© Jenny Phillips

What about fossil fuel sources of energy? We use fossil fuels such as gasoline for fuel in our cars. Coal is burned in power plants and

converted to electricity. If most sources of energy can trace their energy back to the sun, can the energy in fuels such as coal, oil, and

natural gas be traced back to the sun?6

5

Cows eat grass, and as they do so, the energy from the grass is transformed within their bodies to give them energy, help them grow, and eventually give them the energy to produce milk. Milk and other forms of drinks or food are forms of chemical energy that give us energy to live, run, jump, and play!

Most of the energy on the earth can be ed directly back to the sun. We know that the sun’s energy brings the earth heat and light, but how else does the sun bring energy to the earth and all upon it?Let’s take a look at this example:The energy from the sun radiates to the earth. Through a process called photosynthesis, plants on the earth, such as grass, use this energy from the sun to grow.

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8

In recent years, scien sts have discovered and invented many ways to capture the energy of the world. Much of this energy is converted into electrical energy, bringing us the electricity we need to power our homes, stores, and so much more.What types of energy do you see in this picture being captured and converted into electrical energy?

Slowly the trees began to break down and decay. A er a great many years, the weight and heat of the earth caused the remains of the trees to become coal.Today miners dig for coal deep within the earth. The coal is taken to power plants where its chemical energy is converted into electricity.

7

Yes, even fossil fuel energy can be traced back to the sun! Long ago, before God placed man on the earth, plants and trees grew upon the earth as they do now. The sun’s energy radiated down upon the plants, giving them energy to grow. Over me the plants and trees died and gradually became covered with earth.

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Science

Prepara on

Cut a piece of construc on paper into one 8.5 x 8.5 square per child.

Print one copy of the “Frog Hopper” folding instruc on pages.

Print one copy each of the “Poten al Energy” and “Kine c Energy” poster pages.

Print one copy per child of the “Kine c Energy, Poten al Energy” journal page.



Ac vityFollowing the instruc ons on the “Frog Hopper” page, have children each create an origami frog hopper. A er the frogs are made, let the children have fun hopping the frogs about.

Have the children put the frog hoppers aside. Tell the children that they will be learning about the two types of energy their frog hopper exhibited.

Read to children:In this unit we have learned about many forms of energy. Each and every form of energy can be grouped into one of two groups, either kine c or poten al energy.

Poten al energy is stored energy. Show children the “Poten al Energy” poster page. Items have poten al energy when they have energy stored within them with the poten al of being released.

Food is an example of poten al energy. The energy stored in the food has the poten al to be released when eaten and digested.

Wood and other fuels contain poten al energy. Energy is stored within them but not released un l they are burned. When the wood is burned and the energy released, it is no longer poten al energy.

When an item such as an elas c or spring is stretched, the item gains poten al energy. The bowstrings on a bow gain poten al energy as they are pulled back, ready to be released.

All atoms contain energy within them. This energy is poten al energy because it is stored within the atom and will not be released except through nuclear fusion or fi ssion.

An apple hanging on a tree has poten al energy. The apple has poten al energy because of gravity and the apple’s posi on on the tree.

Show children the “Kine c Energy” poster page. When the stem of an apple becomes weakened, and the apple begins to fall, the apple loses poten al energy and gains kine c energy.

Kine c energy is energy in mo on. When items fall or roll down a hill, they have kine c energy. However,

Objec ve

• Help children understand the diff erence between poten al and kine c energy.• Defi ne vocabulary words: poten al energy, kine c energy.

Lesson 5

Lesson 5 - Potential and Kinetic Energy

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Science Lesson 5

falling or rolling is not the only type of kine c energy.

Sound waves are waves of energy moving through the air. Because of their movement, sound waves are kine c energy.

Both light and heat are examples of radia ng energy moving through space. They are both examples of kine c energy.

The movement of electricity through an item is an example of kine c energy. Lightning is kine c energy when the electrical current moves through the clouds and from the sky to the earth below.

All forms of energy have either poten al or kine c energy. Can you think of other examples of kine c and poten al energy? Allow me for sharing.

Let’s think again about our frog hoppers. Use one of the frog hoppers to demonstrate as you explain. As I place my fi nger down against the back of the frog, ge ng it ready to hop, what type of energy does the frog hopper contain? [poten al energy] When I release the frog hopper and it fl ies through the air, what type of energy does the frog hopper now have? [kine c energy]

Science WallPlace the vocabulary cards: poten al energy and kine c energy on the science wall. (These are full pages included in this lesson.)

Science JournalUsing the “Poten al Energy/Kine c Energy” blank journal pages, have children illustrate an example of both poten al and kine c energy.

ProjectHave children build a cra s ck catapult. A er building the catapults, ask the children to demonstrate and explain when poten al and kine c energy are shown in launching an item using the catapult. [Poten al energy is shown when, a er an item is placed on the spoon, the spoon is pressed down and ready for the launch. Kine c energy is shown as the spoon is released and the item fl ies through the air.] Children can launch small, light-weight items such as a mini marshmallow, a

cra pom-pom, a small ball, etc.

How to build the cra s ck tongue depressor catapult:1. Place seven cra s cks on top of each other

and fasten them together using elas c bands wrapped around each end.

2. Place one cra s ck on top of and perpendicu-lar to the bundled cra s cks and one directly beneath.

3. A ach the top cra s ck and the bo om cra s ck together at the same end using an elas c band.

4. Using another rubber band, secure the cra s cks all together across the middle of both.

5. Using two rubber bands, a ach a plas c spoon to the empty end of the top cra s ck.

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Renewable and Non-Renewable Energy Example Cards

Wind The Sun

Water Heat Beneath the Earth

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Older Children: Grades 7-12

Grades 7-12 Unit Extension

EnergyEnergy is something that we are all familiar with and use on a daily basis. But have you ever wondered what energy really is? When you plug a lamp into an electric socket, you see energy in the form of light, but when you plug a heating pad into that same socket, you only feel warmth. When you eat a bowl of spaghetti, the energy it provides helps you to function throughout the day, but when you eat five bowls of spaghetti, some of that energy is turned into body fat.

If you stop to think about it, energy is very complicated. Still, we use energy for every single thing that we do, from the moment we wake up to the moment we go to sleep. Even during the night while we sleep, our body is using energy to do things such as growing bones. Without energy, we couldn’t turn on lights, we couldn’t brush our teeth, we couldn’t make our lunch, and we couldn’t travel to school. Although we all use energy, very few of us understand how we use it.

1. Ability to Do Work

All matter upon the earth has energy. However, energy is not a physical substance. Energy cannot be weighed and doesn’t take up space. Rather energy is the ability to do work. It is a cause or agent of change.

Not all matter contains the same amount of energy. Gas molecules contain more energy than an equal number of liquid molecules (under the same exact conditions) and move more freely than liquid molecules. Liquid molecules contain more energy than solids and move more freely than solids.

2. Forms of Energy

Just as there are many different forms of matter upon the earth, energy also comes in many different forms. We will discuss some of the main forms of energy here.

Radiant energy is the energy of electromagnetic waves or particles. Many forms of energy are radiant energy, including visible light, heat, radio waves, and x-rays.

Solar energy is radiant energy that is put out specifically by the sun.

Thermal energy (sometimes called heat energy) is the energy associated with the microscopic, random motion of particles within matter. In any given substance, the faster the movement of the particles, the hotter the substance becomes. This causes the particles within the substance to space out, becoming less dense.

Light energy is energy that can be seen because it is visible light. Light energy makes it possible to see things when it bounces off objects and enters the eye. Light Energy moves through space as a wave.

Chemical energy is energy due to the way that atoms are arranged in molecules and various other collections of matter. An example of something that stores chemical energy is food. When your body digests and metabolizes food, it utilizes its chemical energy. Another example is gasoline. The energy within gasoline is used to power the engine of a car.

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Electric energy is energy carried by charged electrons moving through a conductor.

Gravitational energy is energy stored in an object above ground. The amount of gravitational potential energy possessed by an object depends on the height of the object above ground. The energy is released when the object moves back to the ground.

Nuclear energy is energy stored within the nucleus of an atom. It is released during nuclear reactions, in which the nucleus splits (nuclear fission) or joins to another nucleus (nuclear fusion). Examples of things that utilize nuclear energy include nuclear power plants and nuclear weapons.

Magnetic energy is energy stored in a magnetic material (iron, cobalt, nickel) that has been moved away from a magnet. It is released when the material moves towards the magnet. An example of something that stores magnetic energy is a superconducting magnet used in an MRI.

Sound energy is energy that is associated with the vibration or disturbance of matter. When objects vibrate they cause sound energy to travel through the air as waves, called sound waves. Sound waves travel at different speeds depending on the material it is passing through. An example of something that creates sound energy is your voice box (larynx).

Mechanical energy is energy that is associated with the motion and position of an object. It is the sum of all of the moving and stored energy that the object has. An example of something that utilizes mechanical energy is a pendulum.

Elastic energy is the energy stored up by pulling, stretching, or compressing an elastic object. Examples of things that store elastic energy include a stretched rubber band or a spring pressed together.

3. Transfer of Energy

A very important law of our universe is that energy is never created nor destroyed, but merely transformed from one form to another.

When we speak of using energy, we are really referring to transferring energy from one place to another. When you use energy to throw a ball, you transfer energy from your body to the ball, and this causes the ball to fly through the air. When you use energy to warm your house, you transfer energy from the furnace to the air in your home, and this causes the temperature in your house to rise. Although energy is used in many different ways, all of these rely on energy being transferred in one of two ways: as heat or as work.

Unfortunately, both “heat” and “work” are common words, so you might think that you already know their meanings. In science, the words “heat” and “work” have very specific definitions that are different from what you might expect. Do not confuse the everyday meanings of the words “heat” and “work” with the scientific meanings.

When scientists speak of heat, they are referring to energy that is transferred from an object with a higher temperature to an object with a lower temperature as a result of the temperature difference. Heat will “flow” from the hot object to the cold object until both end up at the same temperature. When you cook with a metal pot, you witness energy being transferred in the form of heat. Initially, only the stove element is hot – the pot and the

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food inside are cold. As a result, heat moves from the hot stove element to the cold pot. After a while, enough heat is transferred from the stove to the pot, raising the temperature of the pot and all of its contents.

We’ve all observed heat moving from a hot object to a cold object, but you might wonder how the energy actually travels. Whenever an object is hot, the molecules within the object are shaking and vibrating vigorously. The hotter an object is, the more the molecules move around. The more an item is moving, the more energy it has. Hot objects have a lot of energy, and it’s this energy that is transferred to the colder objects when the two come in contact.

Heat is being transferred from a hot object to a colder object. As the red molecules in the hot object move and vibrate, they hit some of the blue molecules in the colder object. This transfers energy from the hot molecules to the colder molecules, causing these molecules to vibrate faster. Just like dominoes, heat passes along the chain until the energy is spread equally between all of the molecules.

Take a close look at the figure to the right. When the vibrating molecules of the hot object bump into the molecules of the colder object, they transfer some of their energy, causing the molecules in the colder object to start vibrating vigorously as well. As these molecules vibrate, they bump into their neighbors and transfer some of their energy on down the chain. In this way, energy passes through the whole system until all of the molecules have about the same amount, and all of the objects are at the same temperature.

Heat is only one way that energy can be transferred. Energy can also be transferred as work. The scientific definition of work is force (any push or pull) applied over a distance. Whenever you push an object and cause it to move, you’ve done work, and you’ve transferred some of your energy to the object. At this point, it’s important to warn you of a common misconception. Sometimes we think that the amount of work done can be measured by the amount of effort put in. This may be true in everyday life, but it isn’t true in science. By definition, scientific work requires that force be applied over a distance. It doesn’t matter how hard you push or how hard you pull. If you haven’t moved the object, you haven’t done any work.

4. Types of Energy: Kinetic and Potential

Machines use energy, our bodies use energy, energy comes from the sun, energy comes from volcanoes, energy causes forest fires, and energy helps us to grow food. With all these seemingly different forms of energy, it’s hard to believe that there are really only two different types of energy – kinetic energy and potential energy.

Kinetic energy is energy associated with motion. When an object is moving, it has kinetic energy. When the object stops moving, it has no kinetic energy. While all moving objects have kinetic energy, not all moving objects have the same amount of kinetic energy. The amount of kinetic energy possessed by an object is determined by its mass and its speed. The heavier an object is and the faster it is moving, the more kinetic energy it has.

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amounts of potential energy because they are made up of different atoms, and those atoms have different positions relative to one another.

Since different chemicals have different amounts of potential energy, scientists will sometimes say potential energy depends not only on position, but also on composition. Composition affects potential energy because it determines which molecules and atoms end up next to each other. For example, the total potential energy in a cup of pure water is different than the total potential energy in a cup of apple juice, because the cup of water and the cup of apple juice are composed of different amounts of different chemicals.

At this point, you might be wondering just how useful chemical potential energy is. If you want to release the potential energy stored in an object held above the ground, you just drop it. But how do you get potential energy out of chemicals? It’s actually not that difficult. You use the fact that different chemicals have different amounts of potential energy. If you start with chemicals that have a lot of potential energy and allow them to react and form chemicals with less potential energy, all the extra energy that was in the chemicals at the beginning, but not at the end, is released.

5. Law of Conservation of Matter and Energy

So far we’ve talked about how energy exists as either kinetic energy or potential energy and how energy can be transferred as either heat or work. While it’s important to understand the difference between kinetic energy and potential energy and the difference between heat and work, the truth is, energy is constantly changing. Kinetic energy is constantly being turned into potential energy, and potential energy is constantly being turned into kinetic energy. Likewise, energy that is transferred as work might later end up transferred as heat, while energy that is transferred as heat might later end up being used to do work.

As we briefly discussed before, energy must follow one fundamental law – Energy cannot be created or destroyed, it can only be changed from one form to another. This law is known as the Law of Conservation of Energy. In a lot of ways, energy is like money. You can exchange quarters for dollar bills and dollar bills for quarters, but no matter how often you convert between the two, you won’t end up with any more or any less money than you started with. Similarly, you can transfer (or spend) money using cash, or transfer money using a credit card, but you still spend the same amount of money, and the store still makes the same amount of money.

As it turns out, the law of conservation of energy isn’t exactly the whole truth. Energy and matter are actually interchangeable. In other words, energy can be created (made out of matter) and destroyed (turned into matter). As a result, the law of conservation of energy has been changed into the Law of Conservation of Matter and Energy. This law states that the total amount of mass and energy in the universe is conserved (does not change).

This is one of the most important laws you will ever learn. Nevertheless, in chemistry we are rarely concerned with converting matter to energy or energy to matter. Instead, chemists deal primarily with converting one form of matter into another form of matter (through chemical reactions) and converting one form of energy into another form of energy.

Let’s take a look at several examples where kinetic energy is switched to potential energy and vice

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Non-Renewable EnergyIn your studies of science, you likely have learned about the process that dinosaur bones turn into fossils. The same processes that formed these fossils also formed some of our most important energy resources. These resources are called fossil fuels. Fossil fuels provide a very high quality energy, but because of our demand for energy, we are using up these resources much faster than they are formed.

As you might guess from their name, fossil fuels are made from fossils. Fossil fuels come from materials that began forming long years ago. As plants and animals died, their remains settled on the ground and at the bottom of bodies of water. Over time, these remains formed layer after layer. Eventually, all of these layers were buried deep enough that they were under an enormous mass of earth. The weight of the earth pressing down on these layers created intense heat and pressure.

After many years of heat and pressure, the material in these layers turned into chemicals called hydrocarbons, which are compounds of carbon and hydrogen. The hydrocarbons in these layers are what we call fossil fuels. The hydrocarbons could be solid, liquid, or gaseous. The solid form is what we know as coal. The liquid form is petroleum, or crude oil. We call the gaseous hydrocarbons natural gas.

You may be surprised to learn that anything that used to be alive could change enough to become something so different, such as coal or oil. There is enough heat and pressure deep below the earth’s surface even to create diamonds, which are the hardest natural material in the world.

Like fossil fuels, diamond is made of carbon. In fact, diamond is a type of pure carbon, so it does not contain the hydrogen that fossil fuels do. What determines whether the remains of living things deep in the earth turn into coal, oil, natural gas, diamond, or something else? All of these materials form under high heat and pressure, but the conditions are different for each material.

Coal

Coal is the solid fossil fuel that formed from dead plants that settled at the bottom of swamps many years ago. The water and mud in the swamps affected how the remains of plants broke down as they were compressed. The water and mud in the swamp kept oxygen away from the plant material. When plants are buried without oxygen, the organic material can be preserved or fossilized. Then, other material, such as sand and clay, settle on top of the decaying plants and squeeze out the water and some other substances. Over time, the pressure removes most of the material other than carbon, and the carbon-containing material forms a layer of rock that we know as coal.

Coal is black or brownish-black in appearance. Coal is a rock that burns easily. Most forms of coal are sedimentary rock. But the hardest type of coal, anthracite, is a metamorphic rock, because it is exposed to higher temperature and pressure as it forms. Coal is mostly carbon, but some other elements can be found in coal, including sulfur.

Around the world, coal is the largest source of energy for electricity. The United States is rich in coal, which is used for electricity.

A common way of turning coal into a useful form to make electricity starts with crushing the coal

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into powder. Then, a power plant burns the powder in a furnace that has a boiler. Like other fuels, coal releases most of its energy as heat when it burns. The heat that the burning coal releases in the furnace is enough to boil the water in the boiler, making steam. The power plant uses this steam to spin turbines, and the spinning turbines make generators turn to create electricity.

For people to use coal as an energy source, they need to get it out of the ground. The process of removing coal from the ground is known as coal mining. Coal mining can take place underground or at the surface. The process of coal mining, especially surface mining, affects the environment. Surface mining exposes minerals from underground to air and water from the surface. These minerals contain the chemical element sulfur, and sulfur mixes with air and water to make sulfuric acid, which is a highly corrosive chemical. The sulfuric acid gets into nearby streams and can kill fish, plants, and animals that live in or near the water. The process of burning coal causes other problems for the environment. A little later, we will look at these other pollution problems when we explore problems with fossil fuels in general.

Oil

Oil is a thick liquid that is usually dark brown or black in appearance. It is found mostly in formations of porous rock in the upper layers of the Earth’s crust. Oil is currently the single largest source of energy in the world. How does oil form? The process of making oil is similar in many ways to the process of making coal. The main difference is in the size of the living things—the organisms—whose remains turn into these fossil fuels. The organisms that die and became the material for making oil are much smaller than the plants that turned into coal. These organisms are called plankton and algae. When the plankton and algae die, their remains settle to the bottom of the sea. There, they are buried away from oxygen, just as the plants did in the process of becoming coal. As layers of sediment pile on top of these decaying organisms, heat and pressure increase. Over a period of many years, the heat and pressure turn the material into liquid oil.

The United States produces oil, although only about one-quarter as much as it uses. The main oil producing regions are the Gulf of Mexico, Texas, Alaska, and California. Most of California’s oil fields are in the Southern San Joaquin Valley. Compression from when the region was a convergent plate boundary produced a set of anticlines that are parallel to the San Andreas Fault. Oil collects in permeable sediments that are capped by an impermeable cap rock. Oil is also pumped on and off the Southern California coast.

Oil fresh from the ground is called crude oil. Crude oil is a mixture of many different hydrocarbons. Oil refining is used to separate the compounds in this mixture from one another. We can separate crude oil into several useful fuels because each hydrocarbon compound in crude oil boils at a different temperature. An oil refinery heats the crude oil enough to boil the mixture of compounds. Special equipment in the refinery separates these compounds from one another as they boil.

Most of the compounds that come out of the refining process are fuels. The rest make up waxes, plastics, fertilizers, and other products. The fuels that come from crude oil, including gasoline, diesel, and heating oil, are rich sources of energy that can be easily transported. Because of this, fuels from

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oil provide about 90% of the energy used for transportation around the world.

We get gasoline from refining oil. Like oil, gasoline is most commonly used for transportation because it is a concentrated form of energy that is easily carried. Let’s consider how gasoline powers a car. Like other fuels you have learned about, gasoline burns and releases most of its energy as heat. When it burns, the gasoline turns into carbon dioxide gas and water vapor. The heat makes these gases expand like the heated air that fills a hot-air balloon. The expanding gases create enough force to move pistons inside an engine, and the engine makes enough power to move the car.

When a resource like gasoline is concentrated in energy, it contains a large amount of energy for its weight. This is important because the more an object weighs, the more energy it takes to move that object. If we could only get a little energy from a certain amount of gasoline, a car would have to carry more of it to be able to travel very far. But carrying more gasoline would make the car heavier, so moving the car would take even more energy. So a resource with highly concentrated energy is a practical fuel to power cars and other forms of transportation.

There are both positives and negatives to using gasoline. Using gasoline to power our vehicles allows us to travel great distances with greater ease and in a much shorter time frame. Unfortunately, using gasoline to power automobiles can affect the environment negatively. The exhaust fumes from burning gasoline include gases that cause many different types of pollution, including smog and ground-level ozone. These forms of pollution cause air-quality problems for cities where large numbers of people drive every day.

We can be conscious in our use of gasoline. We can choose to walk rather than drive to locations that are within walking distance. We can join carpool groups in traveling to school and work, which decreases the number of vehicles in use.

Natural Gas

Natural gas is a fuel that is a mixture of methane and several other chemical compounds. It is often found along with coal or oil in underground deposits. The conditions that create natural gas are similar to those that create oil. In both cases, small organisms called plankton and algae die and settle to the bottom of the sea. In both cases, the remains of these organisms decay without oxygen being present. The difference is that natural gas forms at higher temperatures than oil does.

The largest natural gas reserves in the United States are found in the Rocky Mountain states, Texas, and the Gulf of Mexico region. California also has natural gas, mostly in the Northern Sacramento Valley and the Sacramento Delta. In that region, a sediment-filled trough formed beside an ancient convergent margin. Organic material buried in the sediment hardened to become a shale formation, and that is the source of the gas.

Because it is a mixture of different chemicals, natural gas must be processed before it can be used as a fuel. Some of the chemicals in unprocessed natural gas are poisonous to humans. Other parts, such as water, make the gas a less useful fuel. The processing removes almost everything but methane from natural gas. At this point, the gas is ready to be delivered and used.

Natural gas, often known simply as gas, is delivered to homes for uses such as cooking and heating. Many ranges and ovens use natural gas as a fuel; gas-powered furnaces, boilers, water heaters, and clothes dryers are also common ways that gas is used.

Natural gas is a major source of energy for powering gas turbines and steam turbines to make electricity. When it is used in this way, natural gas works similarly to the way coal does in producing

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energy for electricity. Like coal and other fuels, natural gas releases most of its energy as heat when it burns. The power plant is able to use this heat, either in the form of hot gases or steam from heated water, to spin turbines. The spinning turbines turn generators, and the generators create electricity.

Processing and using natural gas does have some harmful effects on the environment. However, natural gas does burn cleaner than other fossil fuels, meaning that it causes less air pollution. It also produces less carbon dioxide than the other fossil fuels for the same amount of energy.

Problems with Fossil Fuels

Although they are rich sources of energy, fossil fuels do present many problems. Because these fuels are non-renewable resources, their supplies will eventually run out. Safety can be a problem, too, because these fuels burn so easily. For example, a natural gas leak in a building or an underground pipe can lead to a deadly explosion.

Using fossil fuels affects the environment in a variety of ways. There are impacts to the environment when we extract these resources. There are problems that arise because we are running out of supplies of these resources. Burning these fuels can cause air pollution. Air pollution affects both the environment and the health of those people and animals living in the area of the pollution.

Many of the problems with fossil fuels are worse for coal than for oil or natural gas. Coal contains less energy for the amount of carbon it contains than both oil and gas. As a result, burning coal releases more carbon dioxide than burning either oil or gas for the same energy.

Additionally, coal usually contains sulfur. When coal burns, the sulfur goes into the air as sulfur dioxide. Sulfur dioxide is the main cause of acid rain, which can be deadly to plants, animals, and whole ecosystems. Burning coal also puts other polluting chemicals and a large number of small solid “particulates” into the air. These particulates are dangerous to people, especially those who have an illness, like asthma, that makes breathing difficult for them.

Nuclear Energy

When scientists learned how to split the nucleus of an atom, they released a huge amount of energy. This energy is called nuclear energy. Nuclear power plants use uranium that has been processed and concentrated in fuel rods. The uranium atoms are split apart when they are hit by other extremely tiny particles.

Nuclear power plants use the energy they produce to heat water. Once the water is heated, the process is similar to what happens in a coal power plant. The hot water or steam causes a turbine to spin. When the turbine spins, it makes a generator turn, which in turn produces electricity.

The use of nuclear power (nuclear fission) may seem alarming to some. However, nuclear fission is

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not the same as using a nuclear bomb. Explosives cannot directly be made out of uranium. Uranium has to be enriched with plutonium in order to create any type of explosive device. Therefore nuclear power plants cannot explode. Meltdowns, however, can occur if the cooling system of the plant is interrupted.

Nuclear energy does not pollute the air. In fact, a nuclear power plant releases nothing but steam into the air. But nuclear energy does create other environmental problems. The process of splitting atoms creates a dangerous by-product called radioactive waste. The radioactive wastes produced by nuclear power plants remain dangerous for thousands or hundreds of thousands of years. So far, concerns about this waste have kept nuclear energy from being a larger source of energy in this country. Scientists and engineers are looking for ways to keep this waste safely away from people.

Renewable EnergyWhat if we could have all of the energy we needed and never run out of it? What if we could use this energy without polluting the air and water? In the future, renewable sources of energy may be able to provide all of the energy we need. Some of these resources can give us “clean” energy that causes little or no pollution.

Plenty of clean energy is available for us to use. The largest amount of energy to reach Earth’s surface is from solar radiation. Each year 174 petawatts (1.74×1017 W) of energy from the sun enter the Earth’s atmosphere. Because the planet’s interior is hot, heat flows outward from the interior, providing about 23 terawatts (2.3×1013 W) of energy per year. By contrast, the total world power consumption is around 16 terawatts (1.6×1013 W) per year. So solar or geothermal energy alone could provide all of the energy needed for people if it could be harnessed.

Solar Energy

When you think of the sun, you probably think of two things—light and heat. The sun is Earth’s main source of energy, and light and heat are two different kinds of energy that the sun makes. The sun makes this energy when one element, called hydrogen, changes into another element, called helium. Changing hydrogen into helium releases huge amounts of energy. The energy travels to the Earth mostly as visible light. The light carries the energy through the empty space between the sun and the Earth in a process called radiation. We can use this light from the sun as an energy resource called solar energy.

Solar energy is a resource that has been used on a small scale for hundreds of years. Its use on a larger scale is just starting to ramp up as people increase production of renewable energy sources.

Solar energy is used to heat homes, to heat water, and to make electricity. Solar energy can be used to heat the water in your pool or to heat tile floors in your home. In recent years, scientists and engineers have found new ways to get more and more energy from this resource. Because there are many different uses for solar energy, there are also many different

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ways of turning the sun’s energy into useful forms. One of the most common ways is by using solar cells. Solar cells are devices that can turn sunlight directly into electricity. You may have seen solar panels on roof tops. Lots of solar cells make up an individual solar panel.

Solar power plants turn sunlight into electricity using a large group of mirrors to focus sunlight on one place, called a receiver. When a liquid, such as oil or water, flows through this receiver, the focused sunlight heats the liquid to a high temperature. Then this heated liquid transfers its heat by conduction. In conduction, energy moves between two objects that are in contact with one another. The object that is at a higher temperature transfers energy as heat to the object that is at a lower temperature. For example, when you heat a pot of water on a stove top, conduction causes energy to move from the pot to its metal handle, and the handle gets very hot. In the case of the solar power plant, the energy conducted by the heated liquid is used to make electricity.

One of the great benefits of solar energy is that there is plenty of it available. In fact, the amount of energy that reaches Earth from the sun every day is many times more than all of the energy we use. For this reason, we consider solar energy a renewable form of energy. For as long as sunlight continues to warm the Earth, we will never run out of this resource. One problem with solar energy is that it cannot be used at night, unless a special battery stores extra energy during the day for use at night. The technology for most uses of solar energy is still expensive. Until this technology becomes more affordable, most people will prefer to get their energy from other sources. Most of the Earth’s energy comes from the sun. Other renewable resources also come from the sun originally and will be discussed in greater detail later in this article.

Water Power

Earlier in this lesson, you learned that energy can travel in the form of light and heat, just as it does when it travels from the sun to the Earth. Now you will learn about one way that energy can travel in the form of a moving object. In this case, the moving object is water. Water power uses the energy of water in motion to make electricity. It is the most widely used form of renewable energy in the world, and it provides almost one fifth of the world’s electricity.

In most power plants that use water power, a dam holds water back from where it would normally flow. Instead, the water is allowed to flow into a large turbine. Because the water is moving, it has energy of motion, or kinetic energy. The energy of this moving water makes the turbine spin. The turbine is connected to a generator, which makes electricity.

Many of the streams in the United States where water flows down a slope have been developed for hydroelectric power. This is a major source of electricity in some areas of the world.

One big benefit of water power is that it does not burn a fuel. This benefit gives water power an advantage over most other energy resources in how it affects the environment. Because water power does not burn a fuel, it causes less pollution than many other kinds of energy. Another benefit of water power is that, like the other resources, it is a renewable resource. We use energy from the water’s movement, but we are not using up the water itself. Water keeps flowing into our rivers

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and lakes, so wherever we can build plants to use it, water will be available as a source of energy. Additionally, the energy of waves and tides can also be used to produce water power.

Water power does have its problems, though. When a large dam is built, this creates a reservoir, changing the ecosystem upstream. Large river ecosystems are inundated, killing all the plants and animals. The dams and turbines also change the downstream environment for fish and other living things. Dams also slow the release of silt, so that downstream deltas retreat and seaside cities become dangerously exposed to storms and rising seas. Tidal power stations may need to close off a narrow bay or estuary. Wave power applications have to be able to withstand coastal storms and the corrosion of seawater.

Wind Power

As mentioned earlier, the sun provides plenty of energy to the Earth. The energy from the sun also creates wind. Wind happens because the sun heats parts of the Earth differently. For example, sunlight hits the equator much more directly than it hits the North and South Poles. Hot air rises and cooler air moves in, so when the air near the equator is heated much more than the air near the poles, the air begins carrying heat through the air in a process called convection. This movement of air is wind.

Wind power uses moving air as a source of energy. Some examples of wind power have been around for a long time. Windmills have been used to grind grain and pump water for hundreds of years. Ships with sails have depended on wind for even longer. Wind can be used to generate electricity, too. Like the moving water that creates water power, the moving air can make a turbine spin to make electricity.

To help you understand how moving air can be used to make electricity, you could think back to what you have learned about energy of motion, called kinetic energy. Any form of matter that is moving has kinetic energy. Even though you cannot see air, it is matter because it takes up space and has mass. So when wind makes the air move, this air has kinetic energy. When the moving air hits the blades of a turbine, it makes those blades move, and the turbine spins. The spinning of the turbine creates electricity.

Wind power has many advantages. It is clean energy, meaning that it does not cause pollution or release carbon dioxide. Also, wind is plentiful almost everywhere. One problem with wind energy is that the wind does not blow all of the time. One solution is to find efficient ways to store energy for later use. Until then, another energy source needs to be available when the wind is not blowing. Lastly, windmills are expensive and wear out quickly. For the amount of energy they generate, windmills are more expensive than some other forms of renewable energy.

Biomass

Another renewable source of energy is biomass. Biomass is the material that comes from plants and animals that were recently living. Biomass also includes the waste that plants and animals produce. People can use biomass directly for heating. For example, many people burn wood in fireplaces or in wood-burning stoves.

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Besides burning biomass directly for heating, people can process biomass to make fuel. This processing makes what is called biofuel. Biofuel is a fairly new type of energy that is becoming more popular. People can use fuels from biomass in many of the same ways that they use fossil fuels. For example, some mechanics have made changes to car, truck, and bus engines to allow them to use a fuel called biodiesel. Other engines can run on pure vegetable oil or even recycled vegetable oil.

If we use fuels made from biomass, we can cut down on the amount of fossil fuel that we use. Because living plants take carbon dioxide out of the air, growing plants for biofuel can mean that we will put less of this gas into the air overall, which in turn will help the environment.

Geothermal Energy

Geothermal energy is a source of energy that comes from heat deep below the surface of the Earth. This heat produces hot water and steam from rocks that are heated by magma. Power plants that use this type of energy get to the heat by drilling wells into these rocks. The hot water or steam comes up through these wells. Then, the hot water or steam makes a turbine spin to make electricity. Because the hot water or steam can be used directly to make a turbine spin, geothermal energy is a resource that can be used without processing. The fact that it does not need to be processed makes geothermal energy different from most other energy resources. Geothermal energy is clean and safe. It is renewable, too, because the power plant can pump the hot water back into the underground pool. There, the water can pick up heat to make more steam.

This source of energy is an excellent resource in some parts of the world. For example, Iceland is a country that gets about one fourth of its electricity from geothermal sources. In the United States, California leads all states in producing geothermal energy. Geothermal energy in California is concentrated in a few areas in the northern part of the state. The largest geothermal power plant in the state is in the Geysers Geothermal Resource Area in Napa and Sonoma Counties. The source of heat is thought to be a large magma chamber lying beneath the area, a part of the Pacific Ring of Fire. Many parts of the world do not have underground sources of heat that are close enough to the surface for building geothermal power plants.


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Energy Efficiency and Conservation

Imagine that someone offers you a $100 bill that you can use for whatever you want. That would be a pretty good deal, wouldn’t it? Now imagine that the person attaches a condition to their offer: in order to get the $100 bill you have to pay them $75. You would still come out ahead, but this time you would only be getting $25. Does it make sense to spend money to get money? That depends on how much you get back for what you spend.

Getting and using natural energy sources is a lot like spending money to get money. We use a lot of energy just to get energy. We have to find an energy source, extract it from the Earth, transport it to the places where it will be used, and often process or convert it into a different form of energy. All of these steps of getting energy require energy use themselves. For example, we use petroleum to make fuel for our cars. To get the petroleum, we often have to build huge drilling facilities and drill down hundreds of meters into the Earth. It takes energy to do this. We then use trucks or ships to transport the oil all over the world, which also takes energy. We then have to heat the petroleum to its boiling point to make different products from it, like fuel and automotive oil, and this takes even more energy.

In this article, you will learn that different sources of energy all require adding some other energy before they can be made useful. You will be able to compare various sources of energy in terms of their usefulness. You will also learn some ways that we can conserve energy or use it more efficiently.

Obtaining Energy

It takes energy to get energy. Net energy is the amount of usable energy available from a resource after subtracting the energy used to extract it from the Earth and make it usable by humans. We just discussed someone giving you $100 but requiring you to pay them back $75. In this case, your net pay would be $25, or $100 minus $75. Net energy is calculated the same way. For example, for every 5 barrels of oil that we take from the Earth, we have to use 1 barrel for the extraction and refining process. This leaves us a net supply of only 4 barrels (5 barrels minus 1 barrel).

Remember that oil is a non-renewable resource. Imagine what would happen if the energy needed to extract and refine oil increased. What might happen if it took 4 barrels of oil being used to get 5 barrels of new oil? Then our net supply would only be 1 barrel. Our supply of oil would begin to dwindle away even faster than the current rate.

© Jenny Phillips64


We sometimes use the expression (net energy ratio) to demonstrate the difference between the amount of energy available in a resource and the amount of energy used to get it. If we get 10 units of energy from a certain amount of oil, but use 8 units of energy to extract, transport, and refine the oil, then the net energy ratio is 10/8 or 1.25. A net energy ratio larger than 1 means that we are still getting some usable energy. A net energy ratio smaller than one means there is an overall energy loss. The table below shows the net energy ratios for several energy sources commonly used for heating our homes and schools. Higher ratios mean that the source provides more usable energy than those with lower ratios.

Notice from the table that renewable solar energy gives you much more net energy than other sources and that coal-fired electricity actually consumes more energy than it produces. Why do you think this is so? Burning coal for electricity requires a large input of energy to get energy.

Energy Efficiency

The discussion above on net energy shows you that it takes energy to get energy and that some sources of energy require more input than others to get usable energy. After we get the energy, we then use it for some purpose. Energy efficiency is a term that describes how much usable energy we have available to do work from every unit of energy that we use. Higher energy efficiency is desirable because it means we are wasting less energy and getting more use out of the energy sources that we take from the Earth. Higher energy efficiency also lets us extend our non-renewable sources and make them last longer.

Nearly 85% of the energy used in the United States comes from non-renewable fossil fuels. Since these exist in limited supplies, we need to be especially concerned about using them efficiently. Sometimes our choices affect energy efficiency. For example, transportation needs require huge amounts of energy. Forms of transportation such as cars and airplanes are less efficient than transportation by boats and trains. Fluorescent light bulbs are more efficient than regular, incandescent light bulbs. Hydroelectric power plants are more efficient than nuclear fission reactors.

Energy Conservation

Energy conservation involves reducing or eliminating the unnecessary use of energy. This improves energy efficiency. Energy conservation saves us money, and it also ensures that our energy supplies will last longer. There are two main ways to conserve energy: use less energy and use energy more efficiently.

Energy Source Net Energy RationSolar Energy 5.8Natural Gas 4.9Petroleum 4.5Coal-fired Electricity 0.4

introduction to energy...of energy from a certain amount of oil, but use 8 units of energy to...

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