Energy: Energy: What is it? What is it?

Forms and StatesForms and States

Catherine WalkerAmerican Public University

What is Energy?

• Energy is defined as the ability to do work.

• If an object or organism does work, the object or organism uses energy.

• Energy makes everything happen.

Energy is all around you!• You can hear energy as sound.• CRASH! BANG! Did you hear that sound? It was

made by air vibrating.

• You can see energy as light.• Items such as light bulbs and television screens

give off this light energy.

• You can feel energy as wind.• Windmills and sailboats are powered by wind

energy.

Living OrganismsLiving organisms need energy for growth and

movement.

Your body uses energyEven if you’re not moving.

Your body needs enoughfood to keep itself at theright temperature.

You use more energy if you’reActive, and less if you’re resting.

Your body uses energy evenIf you’re asleep or resting.

Energy is needed to pumpBlood around your body.

Food contains nutrients whichProduce energy and help to Grow and repair the body.

We are always using energy• You use energy when you:• Hit a baseball• Ride a bike• Compress a spring • Lift your backpack

How have you used energy today?

Energy is used for…

Can you give an example of how

energy is used for residential and commercial, industrial, or

transportationpurposes?

Energy ConversionEnergy cannot be created or destroyed; it can only be changed from one form to another. When energy changes from one form to another the process is called energy conversion.• The sun’s energy through solar cells can be converted

directly into electricity.• In an electric motor, electromagnetic energy is

converted to mechanical energy.• In a battery, chemical energy is converted into

electromagnetic energy.• The mechanical energy of a waterfall is converted to

electrical energy in a generator.

Green plants convert the sun’s energy into chemical energy through the process of photosynthesis.

Energy Conversion Example

States of Energy

• Kinetic Energy is the energy of motion.• Potential Energy is stored energy.

States of Energy

Kinetic Energy• The energy of motion is called kinetic energy.• The faster an object moves, the more kinetic energy it

has.• The greater the mass of a moving object, the more

kinetic energy it has.• Kinetic energy depends on both mass and velocity.

What has a greater affect on kinetic energy: mass or velocity? Why?

KE = mass x velocity2

2

Potential Energy• Potential Energy is stored energy.• Stored chemically in fuel, the nucleus of atom, and

in foods.• Or stored because of the work done on it:• Stretching a rubber band.• Winding a watch.• Pulling back on a bow’s arrow.• Lifting a brick high in the air (known as

Gravitational Potential Energy).

Gravitational Potential EnergyWater behind a dam, a bolder sitting on a hillside, an apple hanging from tree all have gravitational potential energy.

Gravitational Potential Energy

PE = m (mass) x g (gravity) x h (height)

A cinder block that weighs 60 kilograms is sitting on a platform 20 meters high.

How much gravitational potential energy does it the cinder block have?

60 x 9.8 x 20 = 11,760 Joules of gravitational energy potential

Joules – How Energy is Measured• Both kinetic energy and potential energy are

measured in Joules.

• James Prescott Joules (1818-1889) was a British physicist who established the mechanical theory of heat and discovered the first law of thermodynamics.

• Joules don't equal watts—one is a measurement of energy, one is a measurement of power.

• 1 Watt = 1 Joule used per each second.

Common Forms of Energy

• Chemical• Electrical• Light• Mechanical• Thermal (heat)• Nuclear

Note: Not meant as a complete list of energy types.

Online Quiz

Key Concept: Law of Conservation of Energy• The total amount of energy in the universe is constant.• Energy can be neither created nor destroyed.• It can only be converted from one form to another.

Complete Energy Worksheet

Vocabulary WordsElectrical energyEnergyEnergy conversionGravitational potential energyJoulesKinetic energyLaw of conservation of energyPotential energyLight energyMechanical energyNuclear energyThermal energy

Complete Concept Map

SourcesSlide 1: http://www.conserve-energy-future.com/Images/Energy_Sources.jpg

Slide 2: http://www.unleashyourvitality.com/wp-content/uploads/2010/03/energy.jpg

Slide 4: http://www.grainchain.com/images/topics/11-14/energyOut.png

Slide 5: Baseball: http://www3.pictures.gi.zimbio.com/Olympics+Day+10+Baseball+JOgQPeBHoVrl.jpgBicycle: http://westernskycommunications.com/images/bicycle-photography-ua-criterium-11-cornering.jpgSpring: http://crfsonly.com/howto/keihin-fcr-carb/honda-crf-hot-start/how-to-install-zip-ty-hot-start-nut.phpBackpack: http://www.zimbio.com/pictures/retd20EgMW4/Olympics+Day+10+Baseball/JOgQPeBHoVr/Sun+Lingfeng

Slide 6: http://205.254.135.7/energy_in_brief/major_energy_sources_and_users.cfm

Slide 8: http://www.dynamicscience.com.au/tester/solutions/electric/energyconversions.htm

Slide 9: http://www.petervaldivia.com/technology/energy/image/potencial-and-kinetic.bmp

Slide 10: http://www.youtube.com/watch?v=7K4V0NvUxRg&feature=related

Slide 13:Bolder: http://www.bbc.co.uk/schools/ks3bitesize/science/images/boulder.jpgDam: http://zonalandeducation.com/mstm/physics/mechanics/energy/gravitationalPotentialEnergy/wtrfl1.jpgApple: http://gurneys.com/images/250/12958.jpg

Slide 17: http://glencoe.mcgraw-hill.com/sites/dl/free/0078695104/160350/00076705.swf

Slides 5, 6, 11, 14, 18, 20, and 21: http://bicycledriving.org/enforce/traffic/images/knowledgecheck.jpg

Slide 19: http://www.frankswebspace.org.uk/ScienceAndMaths/physics/physicsGCSE/efficiency.htm

Images used for educational purposes only. PowerPoint inspired by: education.jlab.org/jsat/powerpoint/energy_forms_and_changes.ppt