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_ Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. L 3 _ 8 8 9 4 0 , ,andovenshavethermostats. edn setas hra nry Thermal Energy Reading Essentials Heating Appliances Thermal Energy Transformations Energy Using Thermal Thermal Energy devices generateisnotusedforanypurpose. device. However, thethermalenergythatmostelectronic energy alwaysconvertstothermalinanelectronic warm whenyouusethem.Thisisbecausesomeelectric heating appliances.Computersandcellphonesalsobecome heating appliances. or destroyed.Manydevicestransformener the energytoperformusefultasks.Energycannotbecreated you convertenergyfromoneformtoanother, youcanuse transforming thermalenergyintomechanicalenergy. When other formsofenergy. Thermostatsswitchheatersonandoff, thermal energy. You alsocanconvertthermalenergyinto turn iton.You canconvertotherformsofenergyinto However, thetotalamountofenergydoesnotchange. to anotherortransferenergyfromoneplaceanother. 8 this lesson,reread thestatements to seeifyou have changedyour mind. if you agree withthestatement oraDifyou disagree. After you’ve read whether you agree ordisagree withthem.Place anAintheBefore column What doyou think? . i n eoeSaeetAfter Statement Before d d A energyA device electric intothermalenergy thatconverts isa Burning woodheatstheair. Atoastergetshotwhenyou

1 3 6. 5. Refrigerators cool by moving thermal outside. energy from insidetherefrigerator to the Car engines create energy.

is adevice thatregulates thetemperature ofasystem. Curlingironsandcoffeemakersare Readthetwo statements below anddecide gy fromo ne form ne form

transformation thatoccurs to explaintheenergy afour-tabMake book the lesson. Use thephrasesto review main pointoftheparagraph. paragraph thatsummarizes the Write aphrasebesideeach Identify theMainIdeas • • • Key Concepts in eachdevice.

engine? transformations inacar What are theenergy keep food ? How doesarefrigerator work? How doesathermostat

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0 1 / 5 2 / Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 22/25/10 2:31:13 PM coils liquid Coolant valve Expansion Recall . Heat Refrigerator Heat into room into Heat Most thermostats in home heating heating home in thermostats Most As the air in the room cools, the metal As the air in the nergy, and and nergy, low, pipes that surround the refrigerator are filled low, ation to a warmer location is called a is called location ation to a warmer hrough an fluid, called a coolant, that flows through the pipes. fluid, called a coolant, that flows The cold gas The cold gas A coolant is a substance that evaporates at a low A coolant is a substance that evaporates A device that uses electric energy to transfer thermal energy from a from thermal energy to transfer that uses electric energy A device warmer, and and warmer, the inside of the refrigerator becomes . coolant, which begins as a liquid, passes t expansion valve and cools. flows through pipes inside the absorbs refrigerator, thermal e The vaporizes. coolant gas becomes with a with a transfers to the coolant,Thermal energy inside the refrigerator cold. keeping the inside of the refrigerator temperature. A coolant is pumped through the pipes inside and outside of The the refrigerator. cooler loccooler from a warmer area to athat thermal energy naturally flows the opposite. It moves thermalcooler area. A refrigerator does to the warm air outside. Asenergy from from its cold inside shown be outside. This curls the coil tighter, which tilts the switch in the which tilts the coil tighter, outside. This curls turning on the furnace. other direction, on the inside of the coil contracts more than the metal on the the coil contracts more than the on the inside of Vaporizing the Coolant the Vaporizing Refrigerators Turning a Furnace Off a Furnace Turning a FurnaceTurning On systems contain a bimetallic coil. A bimetallic coil is made of is made coil A bimetallic coil. a bimetallic contain systems into a and bent are joined together of metal that two types expands and inside of the coil metal on the coil. The metal than the in temperature more with changes contracts warms, the thermal After a room of the coil. on the outside uncurl slightly. causes the bimetallic coil to energy in the air that turns off the furnace. This tilts a switch

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What is How does the How d d n i . 8 0 4 9 8 8 Key Concept Check Concept Key _ 3 Reading Check L Visual Check Visual _ E Energy Thermal Reading Essentials R _ 6 92

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_ Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. L 3 _ 8 8 9 4 0 converts thermalenergyintomechanicalenergy. below showshowonetypeofinternalcombustionengine engine called energy thenmovesthecar. Mostvehiclesuseatypeofheat thermalenergyconverts intomechanical energy. edn setas hra nry Thermal Energy Reading Essentials Heat Engines Condensing theCoolant energy fromthegasolineislosttoenvironment. energyingasolineintomechanicalenergy. Theremaining engines convertonlyabout20percent ofthechemical mechanical energy. Aheatengineisnotefficient.Mostcar and someofthethermalenergyimmediatelyconvertsto down. Thefuel’s chemicalenergyconvertstothermal mixture. Theignitedmixtureexpandsandpushesthepiston down. Atoneendofthecylinder, asparkignitesfuel-air the expansionvalve.Thecyclerepeats. becomes aliquid.Theliquidcoolantispumpedupthrough thermal energyisremovedfromthegas,itcondenses,or thermal energytoflowfromthecoolantgasair. As gas isgreaterthanthatofthesurroundingair. Thiscauses through condensercoils.There,thethermalenergyof increases itsthermalenergy. Then,thegasispumped coolant iscompressed,orforced intoasmallerspace,which 8 . i n d d A cylinderisatubewithpistonthatmovesupand A carengineisaheatengine. The coolantflowstoanelectriccompressor. Here,the

Cylinder 1 and airinto thecylinder. drawing ofgasoline amixture the piston moves downward, 1 Intake valve 5

The intake valve opensas an internal engine. The figure an internalcombustionengine.Thefigure Piston mixture. compressing thefuel-air the piston moves upward, 2 Fuel-air mixture

The intake valve closesas Internal Combustion Engine A

Thismechanical isamachinethat piston down. expand, pushingthe burns,mixture hotgases fuel-air mixture. Asthe 3

A sparkplugignites the Spark plug Crankshaft from aheatengine? form ofenergy thatisoutput engine? combustion internal in an ignites thefuel-air mixture 5. State 4. Identify pushed outofthecylinder. and thehotgasesare the exhaust valve opens, 4

Visual Check As thepiston moves up, Key Concept Check What device Exhaust valve What isone Exhaust gases 22/25/10 2:31:32PM / 93 2 5 / 1 0

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0 1 / 5 2 / Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 22/25/10 2:31:51 PM END OF LESSON ED a device that uses electric energy to transfer transfer electric uses to that a device energy a device that regulates the temperature of a system the temperature regulates that a device onnect C thermal energy from a cooler location to a warmer location location a warmer to location cooler a from thermal energy Log on to ConnectED.mcgraw-hill.com ConnectED.mcgraw-hill.com on to Log find this to textbook your and access resources. lesson’s refrigerator: refrigerator: thermostat: Heat engine Heat ____ percent efficient ____ percent cold. a device that converts electric energy electric converts that energy a device 6 1

d a that converts thermal energy into into energy thermal converts a machine that d n i . 8 0 4 Converts Produces 9 8 8 _ 3 L mechanical energy energy mechanical into thermal energy thermal energy into _ E You use some logs to build a campfire. Have you created energy? Destroyed energy? use some logs to build a campfire. You Explain your answer. produces. Complete the graphic organizer to show the types of energy a heat engine converts and Complete the graphic organizer Review the terms and their definitions in the Mini Glossary. Write a sentence explaining a sentence explaining Write Mini Glossary. and their definitions in the Review the terms keeps food how a refrigerator agree with the statement or a D if you disagree. disagree. or a D if you the statement with agree mind? change your Did you Reread the statements at the beginning of the at the beginning the statements Reread with an A if you column in the After lesson. Fill Energy Thermal Reading Essentials R What do you think _ 6 94 3. 2. 1. Mini Glossary engine: heat appliance: heating 1 0 _ 3 1 0 _ 4 5 3 CC354_013_016_RE_L3_889408.indd 16