Presentation on theme: "Energy exists in different forms"— Presentation transcript:
1 Energy exists in different forms Chapter 3.1Energy exists in different forms
2 Energy All forms of energy cause changes to occur Wind causes flag to flutterLight bulb gets hot and glowsYou pick up a tennis racket, change positionHit tennis ballThe ability to cause a changeEnergy takes many different forms and has many different effects.
3 Forms of Energy Scientist classify energy into many forms pg 73 Mechanical EnergySound EnergyChemical EnergyThermal EnergyElectromagnetic EnergyNuclear EnergyEach form causes change in a different way.
4 Mechanical Energy Energy that moves objects Example Energy used to put a book on a shelfEnergy used to turn a key
5 Sound EnergySound results from the vibration of particles in a solid, liquid or gasSound cannot travel through empty space
6 Chemical EnergyEnergy that is stored in the chemical composition of matterAmount of energyDepends on types of atomsDepends on arrangement of atomsExamplesWhen wood or gasoline burns chemical energy produces heatCells use chemical energy that our bodies store from the food we eat
7 Thermal EnergyTotal amount of energy from the movement of particles in matterEnergy of the motion of atoms and molecules
8 Electromagnetic Energy Energy transmitted through space in the form of electromagnetic wavesCan travel through empty spaceThese waves includeVisible lightX-raysMicrowavesSun releases large amount that is absorbed by Earth
9 Nuclear EnergyThe center of an atom, its nucleus, is the source of nuclear energyWhen a heavy atoms nucleus breaks apart energy is releasedWhen the nuclei of two small atoms join together energy is released
10 General Types of Energy All forms of energy can be described in terms of two general types of energyKinetic Energy – energy of motionIncreases as mass increasesIncreases as speed increasesPotential Energy – stored energyDue to position (pg 76)Gravity, stretching, compressingchemical compositionEnergy stored in food, fuel in rocket enginePotential and Kinetic Energy demonstration
11 Energy can change forms but is never lost Chapter 3.2Energy can change forms but is never lost
12 Energy Changes Form How does energy change form? Example – a matchPE is stored in the chemicals on the head of the matchThe flame releases that energy as light and heatConversions between PE and KEExamples – roller coaster, ski jumper, skate boarderUsing Energy ConversionsWater stored behind a dam is changed to electrical energyPg 80 for other examples
13 Law of Conservation of Energy States that energy can neither be created nor destroyed.It may appear that energy is lost or gainedIt only changed form Example 2nd exampleUseful energy is always less than the total amount of energyEnergy conversions may produce unwanted forms of energyElectrical energy may be converted into unwanted sound energy – (ie) a fan
15 Energy EfficiencyMeasurement of usable energy after an energy conversionHigh efficiencyConverts greater percentage of energy into the desired formLow efficiencyConverts a greater percentage of energy into an inefficient form