Transcript Energy Conversion & Conservation

Energy Conversion
&
Conservation
Kim Lachler
NCES: 6.P.1
Updated 2015
Energy Conversion
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the change from one form of
energy to another
Energy.asf
Energy Conversion
Chemical energy
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We get our energy from chemical energy
How_Our_Bodies_Use_Energy.mov
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How_Does_Food_Supply_Energy_.mov
Remember plants get their energy from the sun;
light energy
By using photosynthesis they convert light energy
into sugar- stored energy – potential energy
We eat the plants or animals that eat the plants =
potential energy for us
We either store this energy- in fat – potential
energy or use the energy to move – kinetic energy
Energy Conversion

Calorie – how we measure the potential
energy in food

calorie = 4.2 Kilojoules
Energy Conversion
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A piece of buttered toast contains about 315
kilojoules of energy
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Jog for 6 minutes
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Bicycle for 10 minutes
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Walk briskly for 15 minutes
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Sleep for 1 ½ hours
Energy Conversion

Machines can convert energy to make it into forms
useful for us.
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Alarm clock – electrical energy  light and
sound energy
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Battery – chemical energy  electrical energy
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Light bulb – electrical energy  light and
thermal energy
Energy Conservation
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Any time energy is converted from
one form to another, thermal energy is
given off.
Energy Conservation
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Remember things move from potential energy to
kinetic energy and back again.
As this happens some of the energy is converted
to thermal energy, so the potential energy
becomes less and less.
Energy Conservation
Energy is converted to thermal energy by
friction
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Friction – a force that opposes motion between
two surfaces that are in contact
http://phet.colorado.edu/en/
simulation/friction
Law of conservation of energy

energy can not be created or
destroyed but can be changed
from one form to another
Law of conservation of energy
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Closed system
Where you can measure all the different
energies from start to finish of an action.
The original potential energy = all the final
energies
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mechanical energy ( potential +
kinetic)
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sound energy
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thermal energy
Perpetual Motion
Perpetual motion – a machine that would run forever
without any additional energy
Is this possible?
No, because of friction.
Energy Efficient
comparison of the amount of energy before
a conversion with the amount of useful
energy after a conversion.
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Some machines are not energy efficient –
transferring most of the energy to a form
you don’t want.
Energy Efficient
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Car engine convert only 25% of the
gasoline to kinetic energy, the rest is
converted to thermal energy as a
result of friction.
Energy Efficient
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To help keep machines efficient
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oil
aerodynamic
Bibliography
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Holt,Rinehart and Winsteon, North Carolina Holt Science & Technology, Holt,Rinehart and Winsteon, New
York, 2005
Discovery Education, http://discoveryeducation.com, accessed 12/28/2010
What is a pendulum anyway?, http://www.calacademy.org/products/pendulum/page1.htm, accessed
12/28/2010