GettingtoKnow:PotentialEnergy
Atacompetition, askateboarderbeginshisride teeteringontherimofahalf-pipe.Withaslight leanforward,theskateboardtipsdownontothe ramp.Suddenlytheskateboarderisflyingdown andupagain,soaringrightovertherimand performingtricksinmidair.
Whatgivestheskateboarderenergytoperform suchthrillingtricks?Theskateboarder’sinitial positionatthetopofthehalf-pipegiveshim potentialenergy.Thatpotentialenergychanges tokineticenergy—theenergyofmotion—ashe
movesdownanduptheramp.Theskateboarder’s breakfastalsogavehimpotentialenergy.His musclesreleasesomeofthatenergyastheyworkto twistandturnhisbodythrough tricks.
Whatispotentialenergy?
Potentialenergyisenergythatisstoredinasystem oranobject.This energyhasthepotential todo workwhenitiseventuallyreleased.Theamount of storedenergydependsonanobject’spositionor
Atthetopofa ramp,a skaterhas potentialenergy asaresultofhisposition aboveEarth’ssurface.
condition.Forexample,asaskateboardermovesto apositionhigheraboveEarth’ssurface,hegains potential energy.Whenthispotential energyis released,gravitydoestheworkofmovinghisbody
toanewposition.Thehigherhisinitialpositionabovetheground,themorepotential energyhehasandthefasterandfartherhewill movewhenhefinallybeginsmovingdown.
Misconception1:Energyisamaterialsubstanceor“thing”thatobjectscangain orlose.
Energyisnota“thing.”Itisnotmatter;youcannottouchit.Energyistheabilitytodo work.Inscience,workismovingamassoveradistance.Potentialenergyisstoredenergy. Anobject’spotentialenergycanchangewhentheobject’spositionorconditionchanges.
Potentialenergyalsodependsonanobject’scondition.Thecellsin yourbody,forexample, containchemicalcompounds.Energystoredinthemoleculesofthesecompoundsisreleased duringthechemicalreactionsthatoccurduringcellfunctioning.Ifyouhavenotbeeneating properly,yourcellsmightbeinadepletedconditionandtheywouldstorelesspotential energy.Whenyourcellsarefunctioningnormally,however,theycontainagreatdealof chemicalpotential energy,whichtheytransformintootherkindsofenergyallthetime.This
ishowyouproduce thethermalenergythatkeepsyourbodywarmandthekineticenergy present whenyoumoveyourarmsandlegs.
Concept: Potential Energy Getting to Know
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Doestheskateboarder’spotentialenergydisappearashemoves downtheramp?
No—hispotential energychangesintokineticenergy.Someofthepotential energyhehad atthetopofthehalf-pipechangestokineticenergyashebeginsmovingdownward.Ashe movesupwardontheothersideofthehalf-pipe,someofhiskineticenergychangesbackto potential energy.Kineticandpotential energycontinuallychangefromonetotheotherasa person,oranyobject,movesupanddown.
Misconception2:Someenergyisdestroyedasitchangesform.
Actually,energycanneverreallybecreatedordestroyed.Itsometimes seemslike energygoesaway,forexample,whenamovingobjectcomestoarest.However,thatis theresultofkineticenergychangingtoanother formofenergysuchasheatenergy.
Aretheredifferentkindsofpotentialenergy?
Yes,thereareseveralkindsofpotential energy.The potential energyanobjecthasasaresultofitsheight abovethegroundiscalledgravitationalpotential energy.Gravityhasthepotentialtosettheobject
inmotion.
The atomsandmoleculesthatmakeupyourbody andthefoodyoueathavechemicalpotentialenergy. Thatenergycanbereleasedwhenyouuseyour musclestomoveobjectsorwhenyourbodybreaks downfood.
Thecentersofatomshavenuclearpotential
energy.Hugeamountsofenergycanbereleased
innuclearreactionssuchasthosethatoccurinthe Sun.
Objectsthatcanspringbackafterbeingstretchedorcompressedhaveelasticpotentialenergy. Forexample,whenyouletgoofastretchedrubberband, youreleaseitselasticpotential energy.Thatenergy changestokineticenergyastherubberbandflies throughtheair.
Duringthelesson,youwill learnmoreaboutdifferent kindsofpotential energyandhowpotential energy changestootherformsofenergy.
Foods,likethispineapple,have chemicalpotentialenergy.Yourcells canreleasethatenergyand useitto performlifeprocesses.
Concept: Potential Energy Getting to Know
© Discovery Education.All rights reserved.
2 Discovery Education is a subsidiary
of Discovery Communications, LLC.