Kinetic Energy - The Physics Classroom

Kinetic energy is one of several types of energy that an object can possess. Kinetic energy is the energy of motion. If an object is moving, ...   TPCandeLearning What'sNEWatTPC? ReadWatchInteract PhysicsTutorial 1-DKinematicsNewton'sLawsVectors-MotionandForcesinTwoDimensionsMomentumandItsConservationWorkandEnergyCircularMotionandSatelliteMotionThermalPhysicsStaticElectricityElectricCircuitsVibrationsandWavesSoundWavesandMusicLightandColorReflectionandMirrorsRefractionandLenses PhysicsInteractives AboutthePhysicsInteractivesTaskTrackerUsagePolicyKinematicsNewtonsLawsVectorsandProjectilesForcesin2DMomentumandCollisionsWorkandEnergyCircularandSatelliteMotionBalanceandRotationStaticElectricityElectricCircuitsMagnetismWavesandSoundLightandColorReflectionandMirrorsRefractionandLensesChemistry VideoTutorial KinematicsNewton'sLawsVectorsandProjectilesForcesinTwoDimensionsMomentumandCollisionsWork,Energy,andPowerCircularMotionandGravitationStaticElectricityElectricCircuitsLightandColorReflectionandMirrorsRefractionandLenses MultimediaStudios 1-DimensionalKinematicsNewton'sLawsVectorsandProjectilesMomentumandCollisionsWorkandEnergyCircular,Satellite,andRotationalMotionEinstein'sTheoryofSpecialRelativityStaticElectricityWaves,SoundandLightRayOpticsQuickTimeMovies PracticeReviewTest ConceptBuilders AbouttheConceptBuildersVersion2PricingForSchoolsDirectionsforVersion2MeasurementandUnitsRelationshipsandGraphsKinematicsNewton'sLawsVectorsandProjectilesForcesin2-DimensionsMomentumandCollisionsWorkandEnergyCircularandSatelliteMotionRotationandBalanceStaticElectricityElectricCircuitsWavesandSoundLightandColorReflectionandRefractionChemistry MindsOnPhysics AboutMOPsFeaturesTeacherAccountsPricingForSchoolsTaskTrackerDirectionsKinematicConceptsKinematicGraphingNewton'sLawsVectorsandProjectilesForcesin2-DimensionsMomentumandCollisionsWorkandEnergyCircularandSatelliteMotionStaticElectricityElectricCircuitsWaveMotionSoundandMusicLightandColorReflectionandMirrorsRefractionandLenses CalculatorPad AboutCalcPadTeacherAccountsPricingForSchoolsDirections1DKinematicsNewton'sLawsVectorsandProjectilesVectorsandForcesin2DMomentumandCollisionsWork,Energy,andPowerCircularMotionandGravitationRotationandTorqueStaticElectricityElectricCircuitsVibrationsandWavesSoundWavesLightWavesReflectionandMirrorsRefractionandLensesUnitsandMeasurementMoleConversionsStoichiometry ConceptCheckers TaskTrackerDirections TheReviewSession 1-DKinematicsNewton'sLawsofMotionVectorsandProjectilesForcesinTwoDimensionsMomentumandCollisionsWorkandEnergyPacketCircularMotionandGravitationStaticElectricityReviewElectricCircuitsWavesSoundandMusicLightandColorReflectionandMirrorsRefractionandLenses PhysicsHelp GraphingPracticeRecognizingForcesVectorDirectionVectorAddition ACTTestCenter AbouttheACTACTPreparationACTTipsForTeachersOtherResources Teacher-Tools CurriculumCorner SolutionsGuideSolutionsGuideDigitalDownloadUsagePolicyMotioninOneDimensionNewton'sLawsVectorsandProjectilesForcesinTwoDimensionsMomentumandCollisionsWork,EnergyandPowerCircularMotionandGravitationStaticElectricityElectricCircuitsWaveBasicsSoundandMusicLightandColorReflectionandMirrorsRefractionandLenses QuestionBank ContentsPurchasingtheCDPurchasingtheDigitalDownload NGSSCorner AbouttheNGSSCornerNGSSSearchForceandMotionDCIs-HighSchoolEnergyDCIs-HighSchoolWaveApplicationsDCIs-HighSchoolForceandMotionPEs-HighSchoolEnergyPEs-HighSchoolWaveApplicationsPEs-HighSchoolCrosscuttingConceptsThePracticesPhysicsTopicsNGSSCorner:ActivityListNGSSCorner:Infographics TeacherToolkits AbouttheToolkitsPosition-Velocity-AccelerationPosition-TimeGraphsVelocity-TimeGraphsFreeFallNewton'sFirstLawNewton'sSecondLawNewton'sThirdLawTerminalVelocityVectorsProjectileMotionForcesin2DimensionsImpulseandMomentumChangeMomentumConservationWork-EnergyFundamentalsWork-EnergyRelationshipCircularMotionRollerCoasterPhysicsUniversalGravitationSatelliteMotionChargeandChargingCoulombsLawElectricFieldsCircuitConceptsSeriesCircuitsParallelCircuitsVibrationalMotionDescribing-WavesWaveBehaviorToolkitStandingWavePatternsSoundWavesResonatingAirColumnsWaveModelofLightColorPlaneMirrorsCurvedMirrorsSnellsLawTotalInternalReflectionLenses ReasoningCenter PhilosophyCRSUsageResourceCD TheLaboratory AboutTeacherGuideUsingLabNotebooksShare ThePhotoGallery 1-DKinematicsNewton'sLawsVectors-MotionandForcesinTwoDimensionsMomentumandItsConservationWork,Energy,andPowerCircularMotionandSatelliteMotionThermalPhysicsStaticElectricityCurrentElectricityWavesSoundWavesandMusicLightWavesandColorReflectionandRayModelofLightRefractionandRayModelofLight Store SubscriptionSelectionSeatCalculatorAdFreeAccountMyCart TaskTracker ClassesEditProfileSettingsTasksandCoursesSubscriptionsSubscriptionLocatorTeacherResources   TPCandeLearning What'sNEWatTPC? ReadWatchInteract PhysicsTutorial 1-DKinematics Newton'sLaws Vectors-MotionandForcesinTwoDimensions MomentumandItsConservation WorkandEnergy CircularMotionandSatelliteMotion ThermalPhysics StaticElectricity ElectricCircuits VibrationsandWaves SoundWavesandMusic LightandColor ReflectionandMirrors RefractionandLenses PhysicsInteractives AboutthePhysicsInteractives TaskTracker UsagePolicy Kinematics NewtonsLaws VectorsandProjectiles Forcesin2D MomentumandCollisions WorkandEnergy CircularandSatelliteMotion BalanceandRotation StaticElectricity ElectricCircuits Magnetism WavesandSound LightandColor ReflectionandMirrors RefractionandLenses Chemistry VideoTutorial Kinematics Newton'sLaws VectorsandProjectiles ForcesinTwoDimensions MomentumandCollisions Work,Energy,andPower CircularMotionandGravitation StaticElectricity ElectricCircuits LightandColor ReflectionandMirrors RefractionandLenses MultimediaStudios 1-DimensionalKinematics Newton'sLaws VectorsandProjectiles MomentumandCollisions WorkandEnergy Circular,Satellite,andRotationalMotion Einstein'sTheoryofSpecialRelativity StaticElectricity Waves,SoundandLight RayOptics QuickTimeMovies PracticeReviewTest ConceptBuilders AbouttheConceptBuilders Version2 PricingForSchools DirectionsforVersion2 MeasurementandUnits RelationshipsandGraphs Kinematics Newton'sLaws VectorsandProjectiles Forcesin2-Dimensions MomentumandCollisions WorkandEnergy CircularandSatelliteMotion RotationandBalance StaticElectricity ElectricCircuits WavesandSound LightandColor ReflectionandRefraction Chemistry MindsOnPhysics AboutMOPs Features TeacherAccounts PricingForSchools TaskTrackerDirections KinematicConcepts KinematicGraphing Newton'sLaws VectorsandProjectiles Forcesin2-Dimensions MomentumandCollisions WorkandEnergy CircularandSatelliteMotion StaticElectricity ElectricCircuits WaveMotion SoundandMusic LightandColor ReflectionandMirrors RefractionandLenses CalculatorPad AboutCalcPad TeacherAccounts PricingForSchools Directions 1DKinematics Newton'sLaws VectorsandProjectiles VectorsandForcesin2D MomentumandCollisions Work,Energy,andPower CircularMotionandGravitation RotationandTorque StaticElectricity ElectricCircuits VibrationsandWaves SoundWaves LightWaves ReflectionandMirrors RefractionandLenses UnitsandMeasurement MoleConversions Stoichiometry ConceptCheckers AboutConceptCheckers TeacherAccounts SchoolPricing TaskTrackerDirections TheReviewSession 1-DKinematics Newton'sLawsofMotion VectorsandProjectiles ForcesinTwoDimensions MomentumandCollisions WorkandEnergyPacket CircularMotionandGravitation StaticElectricityReview ElectricCircuits Waves SoundandMusic LightandColor ReflectionandMirrors RefractionandLenses PhysicsHelp GraphingPractice RecognizingForces VectorDirection VectorAddition ACTTestCenter AbouttheACT ACTPreparation ACTTips ForTeachers OtherResources Teacher-Tools CurriculumCorner SolutionsGuide SolutionsGuideDigitalDownload UsagePolicy MotioninOneDimension Newton'sLaws VectorsandProjectiles ForcesinTwoDimensions MomentumandCollisions Work,EnergyandPower CircularMotionandGravitation StaticElectricity ElectricCircuits WaveBasics SoundandMusic LightandColor ReflectionandMirrors RefractionandLenses QuestionBank Contents PurchasingtheCD PurchasingtheDigitalDownload NGSSCorner AbouttheNGSSCorner NGSSSearch ForceandMotionDCIs-HighSchool EnergyDCIs-HighSchool WaveApplicationsDCIs-HighSchool ForceandMotionPEs-HighSchool EnergyPEs-HighSchool WaveApplicationsPEs-HighSchool CrosscuttingConcepts ThePractices PhysicsTopics NGSSCorner:ActivityList NGSSCorner:Infographics TeacherToolkits AbouttheToolkits Position-Velocity-Acceleration Position-TimeGraphs Velocity-TimeGraphs FreeFall Newton'sFirstLaw Newton'sSecondLaw Newton'sThirdLaw TerminalVelocity Vectors ProjectileMotion Forcesin2Dimensions ImpulseandMomentumChange MomentumConservation Work-EnergyFundamentals Work-EnergyRelationship CircularMotion RollerCoasterPhysics UniversalGravitation SatelliteMotion ChargeandCharging CoulombsLaw ElectricFields CircuitConcepts SeriesCircuits ParallelCircuits VibrationalMotion Describing-Waves WaveBehaviorToolkit StandingWavePatterns SoundWaves ResonatingAirColumns WaveModelofLight Color PlaneMirrors CurvedMirrors SnellsLaw TotalInternalReflection Lenses ReasoningCenter Philosophy CRS Usage ResourceCD TheLaboratory About TeacherGuide UsingLabNotebooks Share ThePhotoGallery 1-DKinematics Newton'sLaws Vectors-MotionandForcesinTwoDimensions MomentumandItsConservation Work,Energy,andPower CircularMotionandSatelliteMotion ThermalPhysics StaticElectricity CurrentElectricity Waves SoundWavesandMusic LightWavesandColor ReflectionandRayModelofLight RefractionandRayModelofLight Store SubscriptionSelection SeatCalculator AdFreeAccount MyCart TaskTracker Classes EditProfileSettings TasksandCourses Subscriptions SubscriptionLocator TeacherResources  StudentExtras  Teacher'sGuides ThePhysicsClassroom» PhysicsTutorial»WorkandEnergy»KineticEnergy Work,Energy,andPower-Lesson1-BasicTerminologyandConcepts KineticEnergy DefinitionandMathematicsofWork CalculatingtheAmountofWorkDonebyForces PotentialEnergy KineticEnergy MechanicalEnergy Power Kineticenergyistheenergyofmotion.Anobjectthathasmotion-whetheritisverticalorhorizontalmotion-haskineticenergy.Therearemanyformsofkineticenergy-vibrational(theenergyduetovibrationalmotion),rotational(theenergyduetorotationalmotion),andtranslational(theenergyduetomotionfromonelocationtoanother).Tokeepmatterssimple,wewillfocusupontranslationalkineticenergy.Theamountoftranslationalkineticenergy(fromhereon,thephrasekineticenergywillrefertotranslationalkineticenergy)thatanobjecthasdependsupontwovariables:themass(m)oftheobjectandthespeed(v)oftheobject.Thefollowingequationisusedtorepresentthekineticenergy(KE)ofanobject. KE=0.5•m•v2 wherem=massofobject v=speedofobject Thisequationrevealsthatthekineticenergyofanobjectisdirectlyproportionaltothesquareofitsspeed.Thatmeansthatforatwofoldincreaseinspeed,thekineticenergywillincreasebyafactoroffour.Forathreefoldincreaseinspeed,thekineticenergywillincreasebyafactorofnine.Andforafourfoldincreaseinspeed,thekineticenergywillincreasebyafactorofsixteen.Thekineticenergyisdependentuponthesquareofthespeed.Asitisoftensaid,anequationisnotmerelyarecipeforalgebraicproblemsolving,butalsoaguidetothinkingabouttherelationshipbetweenquantities. Kineticenergyisascalarquantity;itdoesnothaveadirection.Unlikevelocity,acceleration,force,andmomentum,thekineticenergyofanobjectiscompletelydescribedbymagnitudealone.Likeworkandpotentialenergy,thestandardmetricunitofmeasurementforkineticenergyistheJoule.Asmightbeimpliedbytheaboveequation,1Jouleisequivalentto1kg*(m/s)^2. 1Joule=1kg•m2/s2     WeWouldLiketoSuggest... Howdoesacar'sspeed(andthusitskineticenergy)affectthedistancethatwouldberequiredforittobraketoastop?Interact,Explore,andLearntheanswertothisquestionwithourStoppingDistanceInteractive.YoucanfinditinthePhysicsInteractivessectionofourwebsite.TheStoppingDistanceInteractive allowsalearnertoexploretheeffectofspeeduponthestoppingdistanceofatoycar. Visit: StoppingDistanceInteractive       CheckYourUnderstanding Useyourunderstandingofkineticenergytoanswerthefollowingquestions.Thenclickthebuttontoviewtheanswers. 1.Determinethekineticenergyofa625-kgrollercoastercarthatismovingwithaspeedof18.3m/s. SeeAnswer  KE=0.5*m*v2 KE=(0.5)*(625kg)*(18.3m/s)2 KE=1.05x105Joules     2.Iftherollercoastercarintheaboveproblemweremovingwithtwicethespeed,thenwhatwouldbeitsnewkineticenergy? SeeAnswer  Ifthespeedisdoubled,thentheKEisquadrupled.Thus,KE=4*(1.04653x105J)=4.19x105Joules. or KE=0.5*m*v2 KE=0.5*625kg*(36.6m/s)2 KE=4.19x105Joules     3.MissyDiwater,theformerplatformdiverfortheRinglingBrother'sCircus,hadakineticenergyof12000Jjustpriortohittingthebucketofwater.IfMissy'smassis40kg,thenwhatisherspeed? SeeAnswer  KE=0.5*m*v2 12000J=(0.5)*(40kg)*v2 300J=(0.5)*v2 600J=v2 v=24.5m/s   4.A900-kgcompactcarmovingat60mi/hrhasapproximately320000Joulesofkineticenergy.Estimateitsnewkineticenergyifitismovingat30mi/hr.(HINT:usethekineticenergyequationasa"guidetothinking.") SeeAnswer   KE=80000J   TheKEisdirectlyrelatedtothesquareofthespeed.Ifthespeedisreducedbyafactorof2(asinfrom60mi/hrto30mi/hr)thentheKEwillbereducedbyafactorof4.Thus,thenewKEis(320000J)/4or80000J.       NextSection: MechanicalEnergy Power JumpToNextLesson: Internalvs.ExternalForces FollowUs PhysicsTutorial»WorkandEnergy»Lesson1-BasicTerminologyandConcepts»KineticEnergy