The Nature of Energy

1
The Nature of Energy
2
Benchmarks

• Standard III Physical Sciences
• E. Demonstrate that energy can be considered to
  be either kinetic (motion) or potential (stored).
• F. Explain how energy may change form of be
  redistributed but the total quantity of energy is
  conserved.
• G. Demonstrate that waves have energy and waves
  can transfer energy when they interact with
  matter.
• H. Trace the historical development of
  scientific theories and ideas, and describe
  emerging issues in the study of physical
  sciences.

3
What is Energy?

• Energy - ability to do work
• Work - force moves an object a distance
• W Fd
• units are Joules ( J ) for energy
• units for force are Newtons ( N )
• units for distance are meters ( m )
• A Joule can also be considered a Nm

4
States of Energy

• Potential Energy - stored energy, based on
  position of chemical composition
• Gravitational Potential Energy
• GPE mass x gravity x height
• GPE mgh --gt units Joules
• mmass (g) ggravity (9.8 m/s2) hheight (m)
• A 50kg rock is on the edge of a 20m cliff, what
  is its GPE?
• GPE m x g x h
• 50kg x 9.8m/s2 x 20m 9800J

5
States of Energy the Sequel

• Kinetic Energy - energy of motion, based on mass
  and velocity of object
• Kinetic Energy
• KE 1/2 mv2 --gt units Joules
• mmass (g) vvelocity (m/s)
• A 1000kg car is traveling 40m/s, what is its KE?
• KE 1/2mv2
• 1/2 x 100kg x (40m/s)2
• 1/2 x 100kg x 1600m2/s2 80,000J

6
Forms of Energy

• Six Forms of Energy
• Mechanical - moving objects perform work
• Ex wheels turning, hammer hitting a nail, sound
• Chemical - energy stored in the molecules of
  substances
• Ex coal, oil, nature gas, food
• Nuclear Energy - stored in nucleus of atom
• Ex Uranium used for fission

7
Forms of Energy

• Six Forms of Energy
• 4. Heat - energy caused by molecular motion
• Ex Rubbing hands together, lighting a match
• 5. Electrical - flow of electrons through a
  conductor
• Ex computers, televisions, generators
• 6. Light - radiant energy that moves in waves
• Ex sun, light bulbs, electromagnetic energy

8
Conservation of Energy and Matter

• The Law of Conservation of Energy
• energy can be neither created nor destroyed,
  only transformed
• The Law of Conservation of Matter
• matter can be neither created nor destroyed,
  only rearranged
• The total amount of matter and energy in the
  always remains constant in the universe

9
Types of Energy

• RENEWABLE
• Solar energy harnessed from the sun
• Hydroelectric energy harnessed from the
  Potential energy of water
• Biomass energy harnessed agricultural and animal
  waste products
• Wind energy harnessed from the wind
• Geothermal energy harnessed from heat under
  earths crust
• http//library.thinkquest.org/20331/types/

10

• NONRENEWABLE
• Fossil fuels energy from natural gas, petroleum
  and coal
• Nuclear energy from fission and fusion
• What are the advantages and disadvantages of
  each?
• Energy brochure what type of energy do you think
  Ohio should consider to help our energy demands
  and decrease our dependence on coal.
  http//www.puco.ohio.gov/puco/index.cfm/consumer-i
  nformation/consumer-topics/where-does-ohioe28099s-
  electricity-come-from/

11
Energy Transformations

• Energy can transform from one form to another
• Ex A black car absorbs light energy from the sun
  and transforms it to heat energy to warm up the
  car
• During many energy transformations heat is
  produced as an unwanted product
• Ex Motors loose a great deal of energy to
  unwanted heat energy

12
Nuclear Energy

• The three categories of forces are
• Gravitational Forces
• Electromagnetic Forces
• Nuclear Forces
• 1. Strong Force
• 2. Weak Force
• Nuclear forces are the strongest types

13
Fission

• Fission is the process of splitting the nucleus
  of an atom into two lighter weight nuclei
  producing large amounts of energy
• Bombarding Ur-235 or Pu with a neutron causes it
  to split into Kr and Ba, and continues as a chain
  reaction
• Used in nuclear power plants and weapons
• Produces nuclear waste

14
Fusion

• Fusion is the process of combining two or more
  lighter weight nuclei to form a heavier nucleus
  releasing large amounts of energy
• Hydrogen isotopes are converted to Helium under
  extreme temperatures
• Does not produce waste products, has abundant
  resources (Hydrogen), and is safer than fission

15
Nuclear Reactor

• Nuclear reactors control the fission process by
  using the heat produced to produce steam that
  turns a turbine to produce electricity
• The moderator and control rods slow the speed of
  the fission reaction by absorbing neutrons
• There is lead shielding around the core to
  protect against radiation

16
Nuclear Incidents

• Meltdowns
• Chernobyl in Russia
• Recent Tsunami in Japan
• Partial Meltdowns
• -3 mile Island (1979, Harrisburg, Pa)
• -experimental partial meltdowns
• Fermi 1 (1966), Borax-1 (1954)