The Nature of Energy

BenchmarksStandard 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-Complete Calculating Work Practice sheet

What is Energy?

Energy - ability to do workWork - force moves an object a

distanceW = Fdunits are Joules ( J ) for energyunits for force are Newtons ( N )units for distance are meters ( m )

*** A Joule can also be considered a “Nm”

States of Energy Potential Energy - stored energy, based on

position of chemical composition

Gravitational Potential EnergyGPE = mass x gravity x heightGPE = mgh --> units Joulesm=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

-Complete Calculating Power and Potential/Kinetic Energy worksheets

-Complete Calculating Power and Potential/Kinetic Energy worksheets

States of Energy the Sequel Kinetic Energy - energy of motion, based on mass

and velocity of object

Kinetic EnergyKE = 1/2 mv2 --> units Joulesm=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

Forms of Energy

Six Forms of Energy1. Mechanical - moving objects perform work

Ex: wheels turning, hammer hitting a nail, sound

2. Chemical - energy stored in the molecules of substancesEx: coal, oil, nature gas, food

3. Nuclear Energy - stored in nucleus of atomEx: Uranium used for fission

Forms of Energy

Six Forms of Energy4. Heat - energy caused by molecular motion

Ex: Rubbing hands together, lighting a match

5. Electrical - flow of electrons through a conductorEx: computers, televisions, generators

6. Light - radiant energy that moves in wavesEx: sun, light bulbs, electromagnetic energy

Conservation of Energy and Matter

The Law of Conservation of Energyenergy can be neither created nor destroyed, only transformed

The Law of Conservation of Mattermatter 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/

-%efficiency worksheet-%efficiency worksheet

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

Nuclear Energy

The three categories of forces are:

Gravitational Forces Electromagnetic Forces Nuclear Forces

1. Strong Force2. 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)