# CHAPTER 5 Energy And Energy Transformations - Rcboe

1y ago
40 Views
1.43 MB
8 Pages
Last View : 1d ago
Transcription

Conservation of EnergyChanges Between Kineticand Potential EnergyEnergy transformations also occur when you toss a ball upward.The ball slows down as it rises and speeds up as it falls. The ball’sspeed and height change as the energy changes from one form toanother.Kinetic Energy to Potential EnergyIn the figure to the right, notice that the ball is moving fastestand has the most kinetic energy (KE) as it leaves the girl’s hands.As the ball moves upward, its speed and kinetic energy decrease.However, the ball’s potential energy (PE) increases because theball’s height increases. The ball’s kinetic energy is changing topotential energy. At the ball’s highest point, its gravitationalpotential energy is greatest, and its kinetic energy is lowest.Potential Energy to Kinetic EnergyAs the ball moves downward, its potential energy decreases. Atthe same time, the ball’s kinetic energy increases because its speedincreases. As the ball drops, potential energy changes to kineticenergy. When the ball reaches the boy’s hands, the ball’s kineticenergy is once again at its highest value. Energy changes betweenkinetic energy and potential energy as the ball moves. The bars inthe figure show that the ball’s total energy does not change.The Law of Conservation of EnergyThe total energy in the universe is the sum of all the differentforms of energy everywhere. According to the law ofconservation of energy, energy can be transformed from oneform into another or transferred from one region to another, butenergy cannot be created or destroyed. The total amount ofenergy in the universe does not change.Visual Check2. Compare When is thegravitational potentialenergy the greatest?Copyright McGraw-Hill Education.Friction and the Law of Conservation of EnergySometimes it seems as if the law of conservation of energy isnot accurate. Imagine riding a bicycle. The moving bicycle hasmechanical energy. What happens to this mechanical energy whenyou apply the brakes?When you apply the brakes, the bicycle’s mechanical energy istransformed into thermal energy as the brake pads rub against thebicycle’s wheels. The total amount of energy never changes. Theadditional thermal energy warms the brakes, the wheels, and theair around the bicycle.Energy TransformationsKey ConceptCheck3. Define What is the lawof conservation of energy?Energy and Energy Transformations179

Friction and Thermal EnergyVisual Check4. Explain Which type ofenergy is constant in thefigure? Why?Friction When the bicycle’s brake pads rub against the movingwheels, friction occurs. Friction is a force that resists the slidingof two surfaces that are touching. Friction between the brakepads and the moving wheels transforms the bicycle’s mechanicalenergy into thermal energy as shown in the figure above.There is always some friction between any two surfaces that arerubbing against each other. As a result, some mechanical energy isalways transformed into thermal energy when two surfaces rubagainst each other.Reducing Friction It is easier to pedal a bicycle if there is lessKey ConceptCheck5. Specify How doesfriction affect energytransformations?Math SkillswattskWh hours1,000Appliances typically have apower rating measured inwatts (W).Using EnergyYou use different forms of energy to do different things. Youuse radiant energy from a lamp to light a room. You use chemicalenergy stored in your body to run a race. Energy usually changesfrom one form to another when you use it. For example, a lampchanges electric energy to radiant energy that lights a room. Someof the electric energy also changes to thermal energy. Thermalenergy causes the lamp’s bulb to become warm to the touch.Using Thermal EnergyAll forms of energy can be transformed into thermal energy.People often use thermal energy to cook food or provide warmth.A gas stove transforms the chemical energy stored in natural gasinto the thermal energy that cooks the food. An electric spaceheater transforms the electric energy from a power plant into thethermal energy that warms a room. In a jet engine, burning fuelreleases thermal energy that the engine transforms into mechanicalenergy.6. Solve a One-StepEquation A hair dryer israted at 1,200 W. If you usethe dryer for 0.25 h, howmuch electric energy doyou use?180Energy and Energy TransformationsEnergy TransformationsCopyright McGraw-Hill Education.Electric energy often ismeasured in units calledkilowatt-hours (kWh). Tocalculate the electricenergy used by anappliance in kWh, use thisequation:friction between the bicycle’s parts. With less friction, less of thebicycle’s mechanical energy is transformed into thermal energy. Oneway to reduce friction is to apply a lubricant such as oil to surfacesthat rub against each other.

Mini Glossaryfriction: a force that resists the sliding of twosurfaces that are touchinglaw of conservation of energy: energy can betransformed from one form into another ortransferred from one region to another, butenergy cannot be created or destroyed1. Review the terms and their definitions in the Mini Glossary. Write a sentence that provides anexample of friction.2. Use what you have learned about energy to complete the table.Energy ChangeKineticto potentialExampleThrow a ball into the air.Electricto thermalPotentialto kineticEnergy ChangeChemicalto thermalSoundto radiantAn object falls to the ground.Chemicalto electricExampleA call is received on a cell phone.Electricto radiantChemicalto kineticFood is digested to help a personmove.3. Explain one concept you learned from the sentences that you highlighted.Copyright McGraw-Hill Education.What do you thinkReread the statements at the beginning of thelesson. Fill in the After column with an A if youagree with the statement or a D if you disagree. Did you change your mind?182Energy and Energy TransformationsLog on to ConnectED.mcgraw-hill.comand access your textbook to find thislesson’s resources.END OFLESSONEnergy Transformations

Lesson 2Energy TransformationsScan Lesson 2 in your book. Write three questions you have about energy transformations in yourScience Journal. Try to answer your questions as you read.Changes BetweenForms of EnergyIdentify another term for “energy changing form.”I found this on page.Changes BetweenKinetic and PotentialEnergyDescribe how energy changes as a ball is thrown in the air andreturns to the ground. Indicate the relative amounts of potential energyand kinetic energy at each position.I found this on page.Position CPosition BPosition DPosition APosition EPositionKinetic EnergyPotential EnergyABCopyright McGraw-Hill Education.CDEI found this on page.Complete the equation to summarize the ball’s energy changes.Totalenergy ofthe ball energy energyEnergy and Energy Transformations183

Lesson 2 Energy Transformations (continued)The Law ofConservation of EnergyOrganize information about the law of conservationof energy.I found this on page.Law of Conservation of Energyenergy cannot beenergy can be I found this on page.Define friction.I found this on page.Sequence the events that occur as kinetic energy is changedto thermal energy by friction.A boy in-line skates on a hard-surface pathway. This isan example of.The boy applies his brake pad. The pad rubsagainst the surface of the path.changesenergy intoI found this on page.184energy.Identify one way to reduce friction. Include three examples.Energy and Energy TransformationsCopyright McGraw-Hill Education.The boy starts to slow asbetween the pad and the surface of the path

Lesson 2 Energy Transformations (continued)I found this on page.Categorize the change in energy as the boy who was in-line skatingslowed down.1. When the boy was skating, kinetic energy wasthermal energy was, and.2. As the boy applied his brake pad, kinetic energy wasand thermal energy was3. When the boy stopped, kinetic energy wasthermal energy was., and.4. At all times, total energy energy energy.Using EnergyI found this on page.Identify how energy transforms so that it can be used in eachexample.A spaceheater warmsa room.You eat dinner.A radio plays.Copyright McGraw-Hill Education.I found this on page.Relate one way that waste energy is produced.A lightbulb transformselectric energy toandExplain how you know that not all of the electric energy used by a television istransformed to sound and light.Energy and Energy Transformations185

kinetic energy and potential energy as the ball moves. The bars in the figure show that the ball's total energy does not change. The Law of Conservation of Energy The total energy in the universe is the sum of all the different forms of energy everywhere. According to the law of conservation of energy, energy can be transformed from one

Related Documents:

Part One: Heir of Ash Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26 Chapter 27 Chapter 28 Chapter 29 Chapter 30 .

TO KILL A MOCKINGBIRD. Contents Dedication Epigraph Part One Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Part Two Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18. Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26

DEDICATION PART ONE Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 PART TWO Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 .

About the husband’s secret. Dedication Epigraph Pandora Monday Chapter One Chapter Two Chapter Three Chapter Four Chapter Five Tuesday Chapter Six Chapter Seven. Chapter Eight Chapter Nine Chapter Ten Chapter Eleven Chapter Twelve Chapter Thirteen Chapter Fourteen Chapter Fifteen Chapter Sixteen Chapter Seventeen Chapter Eighteen

18.4 35 18.5 35 I Solutions to Applying the Concepts Questions II Answers to End-of-chapter Conceptual Questions Chapter 1 37 Chapter 2 38 Chapter 3 39 Chapter 4 40 Chapter 5 43 Chapter 6 45 Chapter 7 46 Chapter 8 47 Chapter 9 50 Chapter 10 52 Chapter 11 55 Chapter 12 56 Chapter 13 57 Chapter 14 61 Chapter 15 62 Chapter 16 63 Chapter 17 65 .

HUNTER. Special thanks to Kate Cary. Contents Cover Title Page Prologue Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter

Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 . Within was a room as familiar to her as her home back in Oparium. A large desk was situated i

The Hunger Games Book 2 Suzanne Collins Table of Contents PART 1 – THE SPARK Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8. Chapter 9 PART 2 – THE QUELL Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapt