The Nature of Energy

Standard III: Physical Sciences 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.

-Complete Calculating Work Practice sheet 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” -Complete Calculating Work Practice sheet

States of Energy Potential Energy - stored energy, based on position of chemical composition Gravitational Potential Energy GPE = mass x gravity x height GPE = mgh --> units Joules m=mass (g) g=gravity (9.8 m/s2) h=height (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

States of Energy the Sequel Kinetic Energy - energy of motion, based on mass and velocity of object Kinetic Energy KE = 1/2 mv2 --> units Joules m=mass (g) v=velocity (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 -Complete Calculating Power and Potential/Kinetic Energy worksheets

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

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

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

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 earth’s crust http://library.thinkquest.org/20331/types/

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-information/consumer-topics/where-does-ohioe28099s-electricity-come-from/

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 -%efficiency worksheet

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

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

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

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

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)