1. Energy Unit
M,F & E Book – Chapters 5 &6

2. What is Energy? Def: ability to do work or cause change
Needed to cause a change in motion
Measured in Joules
Potential – stored/position
Elastic potential energy
Gravitational potential energy
Weight X Height
Kinetic – motion
½ mass x velocity2

3. Forms of Energy 6 Forms Mechanical Chemical Thermal Nuclear
Moving parts
Chemical
Chemical bonds
Thermal
heat
Nuclear
Nucleus of an atom

4. Conversion – changing from one form to another
Electrical
electricity
Electromagnetic
Light, radiowaves, UV, infrared, gamma rays
Conversion – changing from one form to another
1st law of thermodynamics: some of the energy is always converted to heat
Law of Conservation of Energy
Energy can neither be created nor destroyed, but simply changed to different forms

7. Electrical Energy Energy associated with moving electrons
Common conversion:
Electric motor  converts electric energy to mechanical energy
Electric Battery  converts chemical energy into electric energy
Electric Generator  converts mechanical energy to electrical energy
Electromagnetic Induction
Turbines – large coils of wire that pass through strong magnetic fields

8. Electrical Energy
Ways to Generate Electricity: Coal, Nuclear, Wind, Water, Solar
Alternating Current is used to transmit electricity far distances to homes
Current changes direction
Transformers change voltage
Electrical Power – Voltage X Current
Watts
Electrical Energy – Power X Time
Kilowatt-hours

9. Energy Conversions for Generating Electricity
Think about all the conversions that needed to take place before you used an appliance this morning?
Appliance?
Conversion for Generating Electricity
Before that?

10. Nuclear Energy Fusion – combining two atoms to make 1
Need extremely high temperatures
The Sun
Cold Fusion?
Fission – splitting the atom
Nuclear Power and Nuclear Weapons
Parts of a Nuclear Power Plant: Reactor Core, Fuel Rods, Cooling Tower
Steam is only air emissions
Dangerous Radioactive Waste

11. Electromagnetic Energy
Characteristics
Travels in electric and magnetic waves
Wave Structure
Crest, trough and wavelength
Speed of energy = 300,000 km/sec
Frequency – how many waves go by each second
Hertz – wave per second
Relationships
Shorter the Wavelength: Higher the Frequency
Higher the frequency: Higher the energy
Higher the energy: More Dangerous

12. Types of E-M energy Electromagnetic Spectrum Depends on Wavelength
List from Long to Short Wavelength
Radio waves
Microwaves
Infrared (heat)
Visible Light (ROY B BIV)
Ultraviolet (UV)
X-Ray
Gamma

13. Thermal Energy Deals with movement of particles in matter
Heat vs. Temperature
Heat - amount of thermal energy
Temperature - average speed of the particles
Celsius and Kelvin Scale
Absolute Zero
Is it possible to have more heat but a lower temperature?
Thimble of boiling water vs. Iceburg

14. Thermal Energy
Methods of Heat Transfer  always moves from high heat to low heat
Conduction – direct contact
Warm seat
Convection – carried by fluid currents
Gulf Stream
Radiation – carried by electromagnetic waves (infrared)
Do not need a substance to transfer
Sun’s heat through space
Conductor – heat transfers easily
Insulator – prevents heat transfer
Specific Heat – the amount of heat needed to raise the temperature of 1 kg of a substance by 1o Kelvin

15. Phase Changes Solid, Liquid, Gas or Plasma
Depends on kinetic energy of particles
Melting/Freezing – change between solid and liquid
Water: 0oC (32oF)
Boiling/Condensation – change between liquid and gas
Water: 100oC (212oF)
Evaporation – liquid to gas without reaching boiling point
Sublimation – solid directly to gas without becoming a liquid first
Dry ice
Know how to read Phase Change Graph
Sketch the graph on the next slide and label
Temperature does not change during phase change

16. Phase Changes