Energy

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Energy
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What types of energy are there?
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• What types of energy are there?
• Nuclear
• Fusion
• Fission
• Mechanical (Kinetic)
• Potential
• Gravity
• Springs
• Chemical
• Light
• Heat
• Electrical

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Essentially all energy on Earth comes from a
single source
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FUSION
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THE SUN
Every second, the sun converts 500 million metric
tons of hydrogen to helium. Due to the process of
fusion, 5 million metric tons of excess material
is converted into energy in each second. This
means that every year, 157,680,000,000,000 metric
tons are converted into energy.
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The solar surface
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The Sun
The sun flare ? The corona during an eclipse ?
The aurora
corona during an eclipse
corona during an eclipse
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Nuclear Fusion

• Nuclear fusion is the process by which multiple
  nuclei join together to form a heavier nucleus.
• It is accompanied by the release or absorption of
  energy depending on the masses of the nuclei
  involved..

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Nuclear Fusion of Protons - hydrogen cycle
The Sun derives energy from fusion of protons.
There are many possibilities, but two detailed
cycles were proposed.
The hydrogen cycle H H ? 2D (e) ?
n 2D H ? 3He ? 3He 3He ? 4He 2
Hnet 4 H 4He ( 2e) 2? 2 ? 2 n 26.7
MeV Or Enough energy to keep a 60W light bulb on
for 7 x 10-14 sec
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Nuclear Fusion in Stars
Stars are giant fusion reactors. Nuclear fusion
reactions provide energy in the Sun and other
stars. Solar energy drives the weather and makes
plants grow. Energy stored in plants sustains
animal lives, ours included.
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Nuclear Fusion and the Sun
Sun Mass is 333,000 times that of the Earth. The
sun is a big nuclear fusion reactor, 75 H and
25 He. Sun radius (695000 km) is 109 times that
of the Earth (6.4e3 km). Sun emits 3.86?1026
watts, 8 kwatt/cm2, 1.4 kwatt/m2 reach the
Earths atmosphere (solar constant). 1 kwatt/m2
reaches the Earths surface This is the energy
that drives our weather.
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Matter and Energy

• We have been taught that matter and energy
  cannot be created nor destroyed
• We now need to understand that Matter and Energy
  are two forms of the same thing

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E mc2

• Matter can be changed into Energy
• Einsteins formula above tells us how the change
  occurs
• In the equation above
• E Energy
• m Mass
• c Speed of Light (Universal Constant)

Mass
Energy
Light Speed
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E mc2

• The equation may be read as follows
• Energy (E) is equal to Mass (m) multiplied by
  the Speed of Light (c) squared
• This tells us that a small amount of mass can be
  converted into a very large amount of energy
  because the speed of light (c) is an extremely
  large number

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Fusion

• Fusion is a nuclear reaction whereby two light
  atomic nuclei fuse or combine to form a single
  larger, heavier nucleus
• The fusion process generates tremendous amounts
  of energy refer back to Einsteins equation
• For fusion to occur, a large amount of energy is
  needed to overcome the electrical charges of the
  nuclei and fuse them together

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Fusion

• Fusion reactions do not occur naturally on our
  planet but are the principal type of reaction
  found in stars
• The large masses, densities, and high
  temperatures of stars provide the initial
  energies needed to fuel fusion reactions
• The sun fuses hydrogen atoms to produce helium,
  subatomic particles, and vast amounts of energy

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Review

• Mass and Energy are two forms of the same thing
  neither can be created nor destroyed but mass can
  be converted into energy (E mc2)
• Fission is a nuclear reaction in which a heavy
  atomic nucleus is split into lighter atomic
  nuclei
• Fusion is a nuclear reaction in which 2 light
  atomic nuclei are combined into a single, heavier
  atomic nucleus

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H-bomb
Nov. 1, 1952, the first H-bomb Mike
tested,mushroom cloud was 8 miles across and 27
miles highthe canopy was 100 miles wide, 80
million tons of earth was vaporized. H-bomb
exploded Mar. 1, 1954 at Bikini Atoll yielded 15
megatons and had a fireball 4 miles in
diameter.USSR H-bomb yields 100 megatons.
Tsar 2
The Russian Tsar H-Bomb was the most powerful
ever made
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Nuclear Fusion under Controlled Conditions
Humans had controlled fission chain reactions
before testing bombs. 1952, Nov. 1. US tested
the first H-bomb at Enewetak, controlled
sustained fusion reactor has yet to be
achieved. High temperature and high particle
density for long period of time are the
conditions for fusion. This has not yet been
achieved in a context where more energy is
produced than it costs to make the reaction happen
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Fission

• Fission may be defined as the process of
  splitting an atomic nucleus into fission
  fragments
• The fission fragments are generally in the form
  of smaller atomic nuclei and neutrons
• Large amounts of energy are produced by the
  fission process

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Fission

• Fissile nuclei are generally heavy atoms with
  large numbers of nucleons
• The nuclei of such heavy atoms are struck by
  neutrons initiating the fission process
• Fission occurs due to electrostatic repulsion
  created by large numbers of protons within the
  nuclei of heavy atoms

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Fission

• A classic example of a fission reaction is that
  of U-235
• U-235 1 Neutron
• 2 Neutrons Kr-92 Ba-142 Energy
• In this example, a stray neutron strikes an atom
  of U-235. It absorbs the neutron and becomes an
  unstable atom of U-236. It then undergoes
  fission. Notice that more neutrons are released
  in the reaction. These neutrons can strike other
  U-235 atoms to initiate their fission.

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Fission

• The fission process is an a natural one as a
  French researcher found a natural uranium reactor
  in Gabon, West Africa it has been estimated to
  be over 2 billion years old
• Fission produces large amounts of heat energy and
  it is this heat that is captured by nuclear power
  plants to produce electricity

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Review

• Mass and Energy are two forms of the same thing
  neither can be created nor destroyed but mass can
  be converted into energy (E mc2)
• Fission is a nuclear reaction in which a heavy
  atomic nucleus is split into lighter atomic
  nuclei
• Fusion is a nuclear reaction in which 2 light
  atomic nuclei are combined into a single, heavier
  atomic nucleus

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Quiz

• Which nuclear process produces large amounts of
  energy?
• A. Fission
• B. Fusion
• C. Both fission fusion
• D. Neither fission nor fusion

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Quiz

• Fission is the process that _________ atomic
  nuclei.
• A. Combines
• B. Burns up
• C. Stores
• D. Splits

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Quiz

• Mass may be converted into energy.
• A. True
• B. False

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Quiz

• The fission process requires heavy atomic
  nuclei.
• A. True
• B. False

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Quiz

• Name a nuclear reaction that occurs within the
  sun

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Quiz

• Fission is a natural process that occurs on the
  planet Earth.
• A. True
• B. False

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Quiz

• Explain this equation
• E mc2