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POS

POS. Key Concepts: Heat transfer Insulation and thermal conductivity 2a. Compare heat transmission in different materials (eg. Compare conduction of heat in different solids; compare the absorption of radiant heat by different surfaces. POS.

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POS

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  1. POS • Key Concepts: • Heat transfer • Insulation and thermal conductivity • 2a. Compare heat transmission in different materials (eg. Compare conduction of heat in different solids; compare the absorption of radiant heat by different surfaces

  2. POS • 2b. Explain how heat is transmitted by conduction, convection and radiation in solids, liquids and gases

  3. Unit C: Heat and Temperature Topic 6: Energy Transfer http://www.wisc-online.com/objects/ViewObject.aspx?ID=SCE304

  4. How is energy transferred? • Radiation • Conduction • Convection • Tea light garden pot heater • http://www.bodymindsoulspirit.com/heat-a-room-for-only-15-cents-a-day/

  5. Back up…what is energy? • The ability to do work • Can not be created or destroyed, only transferred • Forms: • Chemical • Mechanical • Electrical • Thermal • Radiant (light) • nuclear

  6. Radiation (energy/transfer) • The only form able to travel through space • Emitted by the sun • Types of EMR Electromagnetic Radiation • Radio waves • Microwaves • Infrared radiation • Visible light spectrum ROYGBIV • UV (ultraviolet) • X-ray • Gamma Ray • Cosmic Rays

  7. Albedo • Radiation is either reflected (by clouds, snow) or absorbed

  8. What makes radiant energy special? • All radiant energy forms • Behave like waves • Can be absorbed and reflected by objects • Travel at the speed of light, 300 000 km/s

  9. Conduction • Learning goals • Be able to explain conduction using the particle model of matter • Be able to explain that different materials conduct energy at different rates • Know that air is among poor heat conductors (insulation)

  10. Conduction • Conduction is the process by which thermal energy is transmitted through collisions between neighboring particles • As temperature increases, particle speed increases, collisions increase, materials heat up more quickly • Common method of energy transfer for solids

  11. Conduction • Conduction occurs when energy is passed directly from one item to another • If you stirred a pot of soup on the stove with a metal spoon, the spoon will heat up. The heat is being conducted from the hot area of the soup to the colder area of the spoon.

  12. metal Air Wood Sleeping bags Good Conductors vs. Bad Conductors (Insulators)

  13. Hot dog/Marshmallow sticks

  14. Convection • Convection is the transfer of energy in fluids, that is, liquids and gases. • Hot fluids rise, cold fluids sink. • Flow is in a circular pattern

  15. Convection-How it works • As temperature (thermal energy) increases: • Particles move faster • Spaces between particles increase • The fluid becomes less dense • Less dense fluids will float on top of more dense fluids • Helium balloons float in air • Molten wax floats on oil • Hot air floats on cold air

  16. Convection-How it works • As temperature (thermal energy) increases: • Particles move faster • Spaces between particles increase (expansion) • The fluid becomes less dense • Less dense fluids will float on top of more dense fluids • Helium balloons float in air • Molten wax floats on oil • Hot air floats on cold air

  17. Convection-How it works • As temperature (thermal energy) decreases: • Particles move slower • Spaces between particles decrease (contraction) • The fluid becomes more dense • More dense fluids will sink

  18. Let’s go back to an earlier lesson and classify each example as • Conduction • Convection • Radiation

  19. Clothing Irons

  20. Clothes dryer

  21. Stove, oven, furnace, fireplace

  22. Thermal energy devices: • Bathroom/bedroom • Hair dryer • Curling/straightening/crimping iron • Electric blanket • Heaters • Radiator • Furnace

  23. Cont’d • Kitchen • Stove • Coffee maker/tea kettle • George Forman grill • Microwave • Other • Fires-camping/candle/fireplace • Clothing Iron • Clothing dryer

  24. Internet link • Learnalberta.ca LA05 7660 • Heat Transfer by conduction Gizmo + questions • http://www.explorelearning.com/index.cfm?method=cExtAccessSecure.dspResource&ResourceID=388

  25. Assignments • Worksheet T6 Radiation/Convection/Conduction • Topic 7+ 8 • Especially note Active and Passive Solar energy • Project pg 234 Making a Transfer • Review Q’s T6 • pg 236 # 4 • Pg 237 #1,2,3,4 • Take your own notes • Watch 1st half of Crude Awakening: The Oil Crash

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