2. content sourcesofenergy

7/27/2019 2. Content Sourcesofenergy

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SOURCES OFENERGY

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What is energy?

Energy makes change; it does things

for us. It moves cars along the road

and boats over the water. It bakes a

cake in the oven and keeps ice frozen

in the freezer. It plays our favorite

songs on the radio and lights our

homes. Energy makes our bodies grow

and allows our minds to think.

Scientists define energy as the ability

to do work. People have learned how

to change energy from one form to

another so that we can do work more

easily and live more comfortably.


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Forms of Energy

Energy is found in different forms,

such as light, heat, sound and motion.

There are many forms of energy, but

they can all be put into two

categories: kinetic and potential.


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KINETIC ENERGYKinetic energy is motionof waves,electrons, atoms, molecules, substances,and objects.Radiant Energy is electromagnetic energythat travels in transverse waves. Radiantenergy includes visible light, x-rays,gamma rays and radio waves. Light is one

type of radiant energy. Solar energy is anexample of radiant energy.


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Thermal Energy

,

or heat, is theinternal energy i

n substances

thevibration and movement of the

atoms and molecules within

substances. Geothermal energy is

an example of thermal energy.

Motion Energy

is the movement ofobjects and su

bstances from one

place to another. Objects and

substances move when a force is

applied according to Newtons Laws

of Motion. Wind is an example of

motion energy.

Sound

is the movement of energythrou

gh substances in longitudinal

(compression/rarefaction) waves.

Sound is produced when a force

causes an object or substance to

vibrate

the energy is transferredthrough

the substance in a wave.


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POTENTIAL ENERGY Potential energy is stored energy and theenergy of positiongravitational energy.There are several forms of potential energy.Electrical Energy is the movement ofelectrical charges. Everything is made of

tiny particles called atoms. Atoms are madeof even smaller particles called electrons,protons, and neutrons. Applying a force canmake some of the electrons move. Electrical

charges moving through a wire is calledelectricity. Lightning is another example ofelectrical energy.


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Chemical Energyis energy stored in the bonds ofatoms and molecules. It is the energy that holdsthese particles together. Biomass, petroleum,natural gas, and propane are examples of storedchemical energy.

Stored Mechanical Energyis energy stored inobjects by the application of a force. Compressedsprings and stretched rubber bands are examplesof stored mechanical energy.

Nuclear Energyis energy stored in the nucleus ofan atomthe energy that holds the nucleus

together. The energy can be released when thenuclei are combined or split apart. Nuclear powerplants split the nuclei of uranium atoms in aprocess called fission. The sun combines the nucleiof hydrogen atoms in a process called fusion.Scientists are working on creating fusion energy onearth, so that someday there might be fusion power

plants. Gravitational Energyis the energy of position or

place. A rock resting at the top of a hill containsgravitational potential energy. Hydropower, suchas water in a reservoir behind a dam, is anexample of gravitational potential energy.


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The sun is the primary source offossil fuels (coal, gas and petroleum).The transfer process began with lifeas plants or animals whose energycame from the sun millions of yearsago


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Understanding renewable andnon-renewable energy


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Most of our energy comes fromnonrenewable energy sources.

Coal, petroleum, natural gas,

propane, and uranium arenonrenewable energy sources.

They are used to make electricity, toheat our homes, to move our cars, and

to manufacture all kinds of products.

These energy sources are callednonrenewablebecause their suppliesare limited. Petroleum, for example,

was formed millions of years ago fromthe remains of ancient sea plants andanimals. We cant make more

petroleum in a short time.
http://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/nonrenewable.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/nonrenewable.html


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Renewable energy sources includebiomass, geothermal energy,hydropower, solar energy, and windenergy.

They are called renewableenergysources because they are replenishedin a short time. Day after day, the sun

shines, the wind blows, and the riversflow. We use renewable energysources mainly to make electricity.
http://www.eia.doe.gov/kids/energyfacts/sources/renewable/renewable.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/renewable/renewable.html


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Law of Conservation ofEnergy Conservation of energy is not saving

energy. The law of conservation of energysays that energy is neither created nordestroyed. When we use energy, it doesntdisappear. We change it from one form of

energy into another. A car engine burns gasoline, converting

the chemical energy in gasoline intomechanical energy. Solar cells changeradiant energy into electrical energy.Energy changes form, but the total

amount of energy in the universe staysthe same. Scientists at the Department ofEnergy think they have discovered amysterious new form of energy called"dark energy" that is actually causing theuniverse to grow!


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Energy Efficiency Energy efficiencyis the amount of useful energy

you get from a system. A perfect, energy-efficientmachine would change all the energy put in itinto useful workan impossible dream.Converting one form of energy into another form

always involves a loss of usable energy. In fact, most energy transformations are not

very efficient. The human body is a goodexample.

Your body is like a machine, and the fuel foryour machine is food. Food gives you the energyto move, breathe, and think. But your body isntvery efficient at converting food into usefulwork. Your body is less than five percentefficient most of the time. The rest of the energyis lost as heat. You can really feel that heatwhen you exercise!


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Heat Heatis the process ofenergytransfer

from one body or systemto another due toa difference in temperature.

Energy transfer by heat can occur

between objects by radiation, conductionand convection. Temperatureis used as ameasure of the internal energy orenthalpy, that is the level of elementarymotion giving rise to heat transfer.

Energy can only be transferred by heatbetween objects - or areas within anobject- with different temperatures
http://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Thermodynamic_systemhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Thermal_radiationhttp://en.wikipedia.org/wiki/Heat_conductionhttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Enthalpyhttp://en.wikipedia.org/wiki/Enthalpyhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Heat_conductionhttp://en.wikipedia.org/wiki/Thermal_radiationhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Thermodynamic_systemhttp://en.wikipedia.org/wiki/Energy


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Heat can move through certainsolids, liquids, and gases.

Heat causes molecules to vibrate.These vibrations are a form ofkinetic or moving energy.

The amount of movement differsbetween solids, liquids, and gases.

A thermometer is a tool used tomeasure temperature.


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Heat causes solids, liquids andgases to expand. Cooling causes solids, liquids and gases tocontract. A solid, like water, can occur in a solid,

liquid, or gaseous state. The amount ofkinetic energy within a sample of waterdetermines the state. Solid water containsthe least amount of kinetic energy. If this

solid is heated, energy will eventually allowthe sample to change to a liquid state, andfinally a gaseous state. It just takes energyinput to cause this to happen.


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A heat conductorreadily conductsthermal energy


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An insulator inhibitsflow of thermal energy.

3 ff t f h t


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3 effects of heatin matter:

1.it changes size2.it changes temperature3.it changes state

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