Transcript The Nature of Energy

The Nature of Energy
What is Energy
• The ability to do work
or cause a change is
called energy.
• When an organism
does work some of its
energy is transferred
to that object.
Operational Definition
• If a system has energy it has the ability to
do something or is actually doing
something.
• A system can contain many forms of
energy.
Kinetic Energy
• Energy of motion is
kinetic energy.
• Two general kinds of
energy – kinetic and
potential.
Kinetic Energy depends on
• Mass and Velocity
• As mass increases so
does the kinetic
energy.
• As velocity increases
so does kinetic
energy.
Potential Energy
• Energy that is stored
is potential energy.
This type of energy
has the potential to do
work.
• Elastic Potential
Energy – is
associated with
objects that can
stretch or compress.
What is work?
• Work is the transfer of energy through
motion.
• The amount of work done depends upon
two things:
• 1. The force exerted
• 2. The distance over which force is
applied.
Gravity?
• Gravitational potential
energy depends on
the height of the
object.
• PE = weight x height
Background info:
• Gravitational PE on an object is = to the
work done to lift it.
• Work = Force x Distance
• Unit for work and energy is the joule which
is = to 1 Newton meter.
Forms of Energy
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Mechanical Energy:
Thermal Energy
Chemical Energy
Electrical Energy
Electromagnetic
energy
• Nuclear Energy
• Sound
• Light
Mechanical Energy
• Energy associated
with the motion or
position of an object.
• Can be Kinetic or
Potential.
Thermal Energy
• Total energy of the
particles in an object.
When thermal energy
increases, its particles
move faster, making it
feel warm to the
touch.
Chemical Energy
• Chemical energy is
potential energy
stored in chemical
bonds that hold the
chemical compounds
together.
Electrical Energy
Moving electrical
charges create
electricity and the
energy they carry is
called electrical
energy.
Electromagnetic Energy
• It is energy that travels in waves. The
waves have some electrical properties and
some magnetic properties.
• Light, infrared, microwaves.
Sound Energy
• Energy produced by vibrations causes
sound.
Light Energy
• Light energy can cause chemical reactions
to occur.
• It provides the energy necessary for
photosynthesis in which green plants
make their own food through a series of
chemical reactions.
• It also stimulates chemical reactions in
your eyes so that you can see.
Conversions
A change from one form of energy
into another.
Law of Conservation of Energy
• This law states that
energy can change
forms but energy
cannot be created or
destroyed under
ordinary conditions.
A system contains
• Input – the things that go into a system to
make it work.
• Output – the things coming out of a
system.
• A system must contain input and output.
Balanced
• Many systems require that the input and
output of the system are balanced which is
not always easy. Consider your own body,
what will happen if the input of energy is
greater than the output of energy?
Power
• Power is the rate at
which work is done in
a unit of time.
• Power = work/time
• Measured in watts
Energy
Sources
Discuss cost
and benefits
of each.
Fossil Fuels
• When plants and animal died, they were
covered with layers of sand, mud, ash,
and other matter. Great pressure, heat,
and bacterial action acted on these buried
organisms forming fossil fuels.
Fossil Fuels
• Fuels store energy in the form of Chemical
PE.
• Fossil fuels include: coal, petroleum, gas.
• The energy fossil fuels store came from
the sun.
• Fossil fuels can be burned to release the
Potential chemical energy this process is
called combustion. PE to thermal E
Examples of Fossil Fuels
• Coal
• Petroleum
• Natural gas
Non-renewable resources
• All fossil fuels are
non-renewable
resources – they
cannot be replaced
after they are used.
• This is why
conservation is so
important.
Nuclear Energy
• Nuclear Energy is stored in the nucleus of
an atom and is released during nuclear
reactions. These reactions release a
tremendous amount of energy. Nuclear
power plants use fission to produce
electricity.
Chain Reaction
• 1. One kind of nuclear
reaction occurs when the
nucleus splits this is
called nuclear fission. In
other words when an
atomic nucleus splits into
two smaller nuclei it is
called nuclear fission.
• When fission reactions
occur in a continuous
process it is called a
chain reaction.
Nuclear Reactor
• The reactor has to control the chain
reaction it uses rods made of boron or
cadmium to absorb some of the neutrons.
The rods can slow down the chain
reaction.
• Eventually energy is released at a
constant rate and this is how electricity is
produced.
Benefits of Nuclear Energy
• Less harmful to environment in that it
produces no air pollution.
Costs of Nuclear Energy
• Hot water from the reactor must cool
before it can enter streams and rivers.
• Possibility of radiation escaping from
power plants.
• The fission products have long half-lives
so they must be stored in containers that
will last the period of the radioactive
decay.
Nuclear waste:
•
Are radioactive by-products that result
when radioactive materials are used.
They are usually classified from high level
to low level wastes for disposal.
• Nuclear waste comes from a variety of
sources and is classified according to the
level of radioactivity.
Spent Fuel
• 1. Spent nuclear
fuel from nuclear
reactors.
• Used fuel pellet
• 2.
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high level radioactive waste from the
reprocessing of spent nuclear fuel.
3. transuranic radioactive waste mainly from
nuclear weapons
4. uranium mill tailings from mining and
milling of uranium
5. low level radioactive waste – generally
waste
from medical and industrial processes.
6. naturally occurring radioactive material.
Low level wastes
• Usually buried in sealed containers in
locations licensed by the government.
High level wastes
• Generated by nuclear
power plants and by
defense research
• Stored in heavily
insulated cooling
pools, and stable
containers.
Of Removing Spent Fuel
from the Reactors to the
Time it’s Ready for
Transport!
Spent fuel is a very intensive
radiation source that is dangerous
for a long time. This high- level
waste must not come into contact
with the biosphere without first being
isolated.
The process of removing spent fuel
from the reactors to the time it is
ready for transport
• Spent fuel stays in the reactor for 3-4 years.
• It is then removed from the reactor. Estimated
that about 2000 tons of spent fuel, expressed as
the amount of original Uranium in the fuel will be
removed from the Finnish reactors during the
projected 40 years of operation.
• Spent fuel contained in transportation
casks are shipped from nuclear power
stations
• Casks are temporarily stored in the
storage area and then sent to the spent
fuel storage building.
• Entire process of removing spent fuel from
a cask to storage pools are performed
underwater.
Spent fuel pool
Step 1: Convectional Nuclear
fuel for Reactors
Once the fuel has served its time in the reactor
it has become spent fuel and is removed from
the reactor and stored at the power station for a
number of months or years to allow cooling.
Following this period it is then ready to be
transported.
Step 2: Transports from power
stations
• Spent fuel are transported from nuclear
power stations usually one flask at a time
• The fuel is stored on site
It’s all about the
process. . .
Nuclear Fusion
• 1. Another kind of reaction occurs when
the nuclei fuse together it is called nuclear
fusion.
• b. HYDROGEN IS THE FUEL FOR THE
SUN’S NUCLEAR REACTIONS.
• THE SUN IS POWERED BY NUCLEAR
FUSION
Nuclear Fusion
• The main fuel for the sun’s nuclear
reactions is hydrogen. Inside the sun
hydrogen nuclei undergo a nuclear
fusion reaction that produces helium
nuclei. As the two hydrogen nuclei
fuse together they release a great deal
of energy. This reaction is the major
source of energy that the sun now
produces.
Alternative Energy Sources
The need for alternatives
Solar Energy
• The sun is the Earth’s
only source of new
energy.
Hydroelectricity
• Hydroelectricity is the
electricity produced by
the energy of moving
water.
• Dams are built to store
water. When the water is
allowed to rush out
through the tunnels it
spins a turbine, rotating
the shaft of an electric
generator to produce
electricity.
Tidal Energy
• The flowing water at
low tied spins a
turbine, which
operates an electric
generator.
Wind Energy
• A windmill is a turbine
that is turned by wind
as it spins it rotates
an electric generator
• A cost of wind energy
is that it looks ugly…
Geothermal Energy
• The inner parts of the
Earth contain thermal
energy. Wells can be
drilled and the steam
from within the Earth
can be used to rotate
turbines.
Carbon Cycle Explanation