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Moving Thermal Energy

1. Moving Thermal Energy. 2. GOALS. Explain common examples, such as ice in a soda, to show the direction of energy flow. Explain molecular motion as it relates to thermal energy changes in terms of conduction, convection, and radiation.

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Moving Thermal Energy

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  1. 1 Moving Thermal Energy

  2. 2 GOALS Explain common examples, such as ice in a soda, to show the direction of energy flow. Explain molecular motion as it relates to thermal energy changes in terms of conduction, convection, and radiation. Differentiate between conduction, convection, and radiation. Determine the heat capacity of a substance using mass, specific heat, and temperature. Use a calorimeter

  3. 3 Temperature and Heat • Temperatureis the measurement of the avg. KE of the molecules in a material. • Heatis the transfer of KE from one material to another. clip

  4. 4 Heat flows from WARMER to COLDER!

  5. 5

  6. 6 Clip Conduction • The transfer of thermal energy in solids. • Materials must be in direct contact with each other! • Ex: Heating of the bottom of a pot on stove.

  7. 7 • clip Convection • Transfer of thermal energy in liquids and gases. • The matter actuallymovesfrom one place to another.

  8. 8 • Clip Radiation • Transfer of thermal energy by electromagnetic waves(we’ll discuses these more later) • Transferring energy through space...NO MATTER IS REQUIRED!

  9. 9 Clip REVIEW

  10. 10 Specific Heat • Adding Energy to a material Causes the • Temperature to go up. • Taking energy away from a substance causes the temp. to • Go down!

  11. 11 • Have you ever noticed that on a hot summer day the pool is cooler than the hot cement? • OR maybe that the ocean is cooler than the hot sand? • Why? The sun has been beating down on both of them for the same amount of time........... • It takes more thermal energy to raise the temperature of water that it does the cement!

  12. 12 Water absorbs a lot of heat energy before its temperature changes while sand needs little heat energy before its temperature increases.

  13. 13 Specific Heat • The amount of energy required to raise the temperature of a material (substance). • It takes different amts of energy to make the same temp change in different substances. • We call the amt required: Specific Heat!

  14. 14 Example:Specific Heat of Water • Cp = 4,184 Joules of energy to raise the temperature of 1kg 1°C. • video clip Why Cp? Cp Stands for “Heat Capacity”

  15. 15 Specific Heat of water • The Cp is high because H2O mols. form strong bonds w/each other. • It takes a lot of energy to break the bonds so that the the molecules can then start to move around faster (HEAT UP).

  16. 16 Calculating Specific Heat The Greek letter Δ means “change in”

  17. 17 EXAMPLE : p162 • Mass = 45kg • Q = 203,000J • Δt = 40°-28° • Δt = 12° • Cp = ? • Q =m x Cp x Δt • Q/(m x Δt) = Cp • Cp = 376 J/(kg °C)

  18. 20 EOCT QUESTION

  19. 21 Conduction can BEST be described asthe transfer of energy A by traveling through space as waves B by the movement of fluids C by the expansion of gases D by contact between particles

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