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Energy - PowerPoint PPT Presentation

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Energy. Energy Sources and Energy Conversions. Objectives. Describe an energy conversion. Give examples of energy conversions among the different forms of energy. Explain how energy conversions make energy useful. Know the non-renewable and renewable sources of energy. Energy Conversion.

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Energy Sources and Energy Conversions



Describe an energy conversion.

Give examples of energy conversions among the different forms of energy.

Explain how energy conversions make energy useful.

Know the non-renewable and renewable sources of energy.


Energy Conversion

A change from one form of energy to another.


Energy Conversion on a Trampoline

#3 – At the top of the jump, all of the kinetic energy has been converted into potential energy.

#1 – Stretching the trampoline is like stretching a rubber band. Potential energy is stored.

#4 – Just before hitting the trampoline, all of the potential energy has been converted into kinetic energy.

#2 – As the person leaves the trampoline, the potential energy is converted into kinetic energy.


More Energy Conversions

Alarm Clock

electrical → light & sound


chemical → electrical

Light Bulb

electrical → light & heat


electrical → kinetic & sound



Any questions?

Complete 'Energy conversions' worksheet.

What energy conversion is taking place in this video? ForTheBirds.flv

Video to demonstrate energy can not be created or destroyedCanYouCreateEnergy!!!!.flv


Energy & Machines

  • Machines make work easier by changing the size or direction of the force.

  • When you use a machine, you transfer your energy to the machine, and the machine transfers that energy to the object.


Importance of Energy Conversions

A way of getting the form of energy that YOU need.

Converting energy to a useable form increasing energy efficiency and reduces energy waste


Non-renewable sources of energy

  • Burning coal, natural gas, turf and petroleum releases energy stored in the fuel as heat. The energy contained by the fuels is derived from the energy of the sun.

  • ..\..\..\..\..\Videos\RealPlayer Downloads\Fossil-Fuelled Electricity - How it Works.flv


Pollution Problem

  • Global warming is/may be caused by the "Greenhouse effect." (accumulation of carbon dioxide in our earth's atmosphere) A layer of gas forms that traps heat inside the atmosphere, thereby acting as the glass ceiling of a greenhouse. Because heat is trapped by the carbon dioxide, it is believed that the earth is slowly warming.

  • National Geo carbon emissions.pdf

  • A potential (but relatively distant) danger of global warming is the melting of the so-called "polar ice caps" at the north and south poles. This occurrence would cause the ocean level to rise and perhaps flood many coastal cities.

  • Before humans were around on the earth, there was a relatively even recycling of carbon dioxide and oxygen. Plants require carbon dioxide to live, and they emit oxygen in return. Animals, on the other hand, need oxygen, but exhale carbon dioxide. But as humans began to burn fossil fuels to create energy (especially beginning just before the 20th century during the "Industrial Revolution"), more and more carbon dioxide was emitted into the air until the balance was slowly destroyed.



  • Write down 2 advantages of fossil fuels as a source of energy


Nuclear energy

  • ..\..\..\..\..\Videos\RealPlayer Downloads\Nuclear Power - How it Works.flv

  • Having watched this video do you think nuclear energy is a renewable or non-renewable source of energy?


Renewable Sources of Energy(1) Hydro-electricity

  • Hydroelectric systems make use of the energy in running water to create electricity.

  • Changes in Energy (Hydro electric energy) (clip).flv

  • Water has kinetic energy when it flows from higher elevations to lower elevations. This energy spins turbines.


(1) Hydro-electricity

  • Advantages

  • Inexhaustible fuel source

  • Minimal environmental impact

  • Viable source--relatively useful levels of energy production

  • Can be used throughout the world

  • Disadvantages

  • Smaller models depend on availability of fast flowing streams or rivers

  • Can impact the mobility of fish and other river life. NOTE: Building a fish ladder can lessen this negative aspect of hydroelectric power.

  • Can alter the water quality, in turn impacting on the wildlife.


(2) Solar energy

Most of the energy known to man is derived in some way from the sun. When we burn wood or other fuels, we are releasing the stored energy of the sun. In fact, there would be no life on earth without the sun, which provides energy needed for the growth of plants, and indirectly, the existence of all animal life.

There are two ways in which solar power can be converted to energy using solar panels. The first involves using the energy of the sun to directly heat air or a liquid. The second involves converting solar energy directly to electricity.


(2) Solar Power

  • Advantages

  • Inexhaustible fuel source

  • No pollution

  • Often an excellent supplement to other renewable sources

  • Versatile--is used for powering items as diverse as solar cars and satellites

  • Disadvantages

  • Very diffuse source means low energy production--large numbers of solar panels (and thus large land areas) are required to produce useful amounts of heat or electricity

  • One major concern is the cost of solar power. Solar panels are not cheap; and because they are constructed from fragile materials; they must constantly be maintained and often replaced.


(3) Biomass

  • Biomass is simply the conversion of stored energy in plants into energy that we can use.

  • Biomass includes wood, crops & grasses, wastes and aquatic plants.

    Biofuels - National Geographic Magazine


(4) Geothermal

  • The word geothermal comes from the Greek words geo (earth) and therme (heat). So, geothermal energy is heat from within the earth. We can use the steam and hot water produced inside the earth to heat buildings or generate electricity. Geothermal energy is a renewable energy source because the water is replenished by rainfall and the heat is continuously produced inside the earth.


  • Geothermal energy is generated in the earth's core, about 4,000 miles below the surface. Temperatures hotter than the sun's surface are continuously produced inside the earth.


(5) Wind energy

  • Wind generators take advantage of the power of wind. Long blades, or "rotors", catch the wind and spin. Like in hydroelectric systems, the spinning movement is transformed into electrical energy by a generator


(5) Wind energy

  • One of the main problems with wind power is the space that is used up by the so-called "wind farms." In some cases, the space taken up can seriously alter the environment.

  • The good news is that although wind farms require a great deal of square mileage, there is quite a bit of space between the actual wind machines. This space can be used for agricultural purposes.

  • Another problem with wind power is that relatively speaking, it does not generate very much energy for the price. Perhaps this setback is made up for in friendliness to the environment.


(6) Tidal/Wave energy

Tides are caused by the gravitational pull of the moon and sun, and the rotation of the earth. Waves are caused by the wind blowing over the surface of the ocean. The energy of this moving water can be harnessed to generate electricity.

Although tidal and wave energy don't produce pollution, they can cause other environmental problems. Can you think of any?


To sum up……

..\..\..\..\..\Videos\RealPlayer Downloads\Renewable Energy.flv


For the Birds clip:

Fossil fueled electricity:

National Geographic - carbon emissions: attached above.

There are two articles in the national geographic magazine (you can look up the website) from October 2007 entitled 'The Carbon Crisis' and 'Growing Fuel'. I read some of the first article in class and it really got them talking.

Nuclear Power:

Hydro electric: