Transcript Chapter 5 Notes

Chapter 5
Energy and Energy Resources
5 – 1 What is Energy ?
What is Energy ?
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Energy – the ability to cause change.
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Everything has energy.
Any time a change occurs, energy is
transferred from one object to another.
Kinetic Energy
Kinetic Energy the energy an object
has due to its motion.
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An object must be moving in order to
have Kinetic Energy.
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2 factors determine Kinetic Energy
1.
2.
Velocity of the object
Mass of the object
Potential Energy
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Potential Energy – the energy stored
in an object because of its position.
2 factors determine Potential Energy
1.
2.
Height above the floor
Mass of the object
Thermal Energy
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Thermal Energy – the sum of the kinetic
energy and potential energy of an
object.
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All objects have thermal energy.
Thermal energy increases as an objects
temperature increases.
Chemical Energy
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Chemical Energy – the energy stored in
the chemical bonds.
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Food supplies energy when the body
breaks these chemical bonds down and
releases the stored energy.
Fuel supplies energy when it is burned,
breaking the chemical bonds and releasing
the energy.
Radiant Energy
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Radiant Energy – the energy carried by
light.
The radiant energy is absorbed,
transmitted, or reflected.
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Absorbed radiant energy is transformed
into thermal energy.
Transmitted radiant energy passes through
the object unchanged.
Reflected radiant energy bounces off of the
object.
Electrical Energy
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Electrical Energy – the energy that is
carried by electric current.
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The amount of electrical energy is
measured in voltage.
20 % of the U.S. electrical energy is
produced by nuclear generators.
Nuclear Energy
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Nuclear Energy – the energy contained
in atomic nuclei.
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Releasing this energy is difficult and leaves
radioactive pollution that must be safely
stored for millions of years.
5 – 2 Energy Transformations
Law of Conservation of Energy
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Law of Conservation of Energy- energy
is neither created nor destroyed.
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Energy can change the form in which it
appears.
Example
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Identify the energy changes as you
throw a ball up in the air, and then
catch it as it falls back down.
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Track the energy changes as a car
accelerates, then comes to a stop.
Generating Electrical Energy
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Power plants use a Generator.
Generator – a device that converts
kinetic energy into electrical energy.
Coal ( or some other fossil fuel ) is
burned to release its chemical energy
as thermal energy.
That thermal energy is used to turn
liquid water into steam.
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The steam is used to turn a Turbine.
The turbine turns the generator,
changing the kinetic energy into
electrical energy.
5 – 3 Sources of Energy
Energy Resources
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The surface of Earth receives energy
from two sources :
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Sun
Radioactive atoms inside the Earth
Nearly all the energy
we use comes from the
Sun
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Fossil Fuels
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Fossil fuels include Coal, Oil and Natural
Gas.
Oil and Natural Gas were formed from
the remains of microscopic organisms
that lived in oceans millions of years
ago.
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Coal was formed from the remains of
plants that lived on land millions of
years ago.
Using Fossil Fuels
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Nonrenewable Resource – an energy
resource that is used up much faster
than it can be replaced.
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Fossil Fuels are nonrenewable.
Burning fossil fuels creates chemical
compounds that cause pollution.

They cause respiratory illness and acid
rain.
Nuclear Energy
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Nuclear energy production takes place
much like coal fired power plants.
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Nuclear power plants produce almost
no air pollution.
Nuclear power plants help make the
supply of fossil fuels last longer.
Nuclear Energy is nonrenewable.
The waste produced is highly
radioactive.
Renewable Energy
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Renewable Energy – an energy
resource that is replenished continually.
Hydroelectricity
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20 % of the world’s energy is supplied
from hydroelectricity.
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Hydroelectricity is the largest renewable
energy resource.
There is no pollution produced.
Hydroelectricity disrupts the life cycle of
fish and other aquatic organisms.
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Fish ladders can be installed.
Very expensive solution.
Alternative Energy Resources
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Alternative Energy Resource – new
sources of energy that are safer and
cause less harm to the environment.
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Solar
Wind
Geothermal
Solar Energy
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The Sun is the source of nearly all the
energy on Earth.
The Sun is an inexhaustible source of
energy.
Inexhaustible Resource – an energy
source that cannot be used up by
humans.
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Less than 0.1 % of the energy used in
the USA comes from the Sun.
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Solar Energy is more expensive than fossil
fuels.
Solar Heating
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Solar collectors absorb the radiant
energy from the Sun and store it in
water.
The water is then pumped throughout
the house to warm the house.
Photovoltaic
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Photovoltaic – a device that converts
the radiant energy from the Sun into
electrical energy.
Geothermal Energy
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Geothermal Energy - Heat that is
generated inside the Earth.
The magma under the surface heats the
rock around it.
If this is near the surface of the Earth,
rainwater that seeps down can become
heated and form geysers.
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Wells can be drilled down to heat water
and use it for heating and electrical
production.
Geothermal is an inexhaustible
resource.
Can only be located in certain areas of
the Earth.
Heat Pump
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A closed loop of water is pumped down
into the Earth and then back up to the
surface.
In the winter, the underground
temperature is greater than the air
temperature.
In the summer, the underground
temperature is less than the air
temperature.
Energy from the Oceans
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The rise and fall of the tides can be
converted into electrical energy.
The mechanical energy of the water can
be transformed into electrical energy.
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There is no pollution from using tidal
energy.
It is an inexhaustible source of energy.
It is limited to only a few places on
Earth where the rise and fall of the tide
is large enough to justify building a
large generating plant.
Wind
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Kinetic energy of the wind is converted
into electrical energy.
They require large areas of land.
They make noise pollution.
Conserving Energy
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One can conserve energy in order to
make fossil fuels last longer.