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## The Nature of Energy

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### The Nature of Energy Benchmarks Standard III: Physical Sciences E. Demonstrate that energy can be considered to be either kinetic (motion) or potential (stored). – PowerPoint PPT presentation

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Title: 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 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

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)