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Thermal Energy and Heat

Thermal Energy and Heat

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Thermal Energy and Heat

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  1. Thermal Energy and Heat

  2. 3 Ways heat is transferred • Conduction • Convection • Radiation • Overview of the process (Click Here)

  3. CONDUCTION • The transfer of thermal energy in materials that are touching. • Occurs as particles collide

  4. Conduction • Involves no overall transfer of matter • Takes place more easily in solids than in liquids or gases.

  5. Conductors • A material that conducts thermal energy well. • HEAT moves quickly.

  6. Insulators • Poor conductors of thermal energy • Heat moves slowly. • Examples:

  7. Insulators

  8. Insulators

  9. Why do tile floors feel colder than wooden floors?

  10. Why do tile floors feel colder than wooden floors? • Both floors are the same temperature. • The tile floor is a better conductor than the wood floor. • A material that is a good conductor moves heat quickly. • The heat moves quickly from your feet (warmer) to the tile, making your feet cooler, making it seem as though the tile is colder than the wood.

  11. Why does your tongue stick to a pole on a freezing cold day?

  12. Conclusion • The direction of heat flow depends on: The temperature (Heat always moves from HOT to COLD) • The speed of heat flow depends on: The ability to conduct. (Good conductors moves heat faster)

  13. Convection • The transfer of thermal energy by the movement of FLUIDS (liquid or gas) with different temperatures.

  14. Convection Current • When you heat up a liquid or gas the molecules move faster, and spread out and become less dense. • Since it is less dense it rises. • After it rises, it is away from the heat source and cools. • Once it is cool, it sinks.

  15. Thermal contraction • As an object cools, the particles of matter are able to move closer together. This causes the density to increase. (D=m/v, if the volume is less the density goes up)

  16. Thermal expansion Particles of matter move farther apart as they move faster as the temperature increases. This causes the density to decrease.

  17. Convection Current

  18. Convection Currents

  19. Convection currents

  20. Home heating and convection currents

  21. Radiation • The transfer of thermal energy by electromagneticwaves traveling through space.

  22. Radiation • Does NOT involve the movement of particles. • Is the only form of transfer of thermal energy that can occur in space.

  23. Radiation Shiny objects reflect electromagnetic energy Dull, dark objects absorb electromagnetic energy Absorbed electromagnetic energy is converted into thermal energy.

  24. Radiation • As an object’s temperature increases, the rate at which it radiates energy increases.

  25. Radiation

  26. Radiation

  27. Review • Heat transfer review • mini quiz