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Topic V:

Thermodynamics and Heat Energy. Topic V:. Energy. I. A. The Earth receives energy from the sun in the form of Electromagnetic Radiation. • Energy that travels in the form of electromagnetic waves at LIGHT SPEED!.

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Topic V:

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  1. Thermodynamics and Heat Energy Topic V:

  2. Energy I. A. The Earth receives energy from the sun in the form of Electromagnetic Radiation. • Energy that travels in the form of electromagnetic waves at LIGHT SPEED!

  3. • Electromagnetic energy comes in many forms that are listed in the Electromagnetic Spectrum  Where can you go to see the spectrum?

  4. Example: Wave Diagram

  5. B. Electromagnetic radiation from the Sun does several things when it hits our planet 1. It can be reflected: bounces off 2. It can be refracted: gets “bent” or “scattered” 3. It can be absorbed: taken into the material 4. It can be transmitted: allowed to pass through  Rule: Good absorbers are good emitters! (of radiation)

  6. C. Different materials reflect/refract/absorb energy at different rates • Depends on:  Texture  Rough Texture = More Absorption = More Release

  7.  Color  Darker Color = More Absorption = More Release  Shiny Color = More Reflection = Less Release

  8. Energy Transfer II. A. Radiative Balance: Earth emits the same amount of energy it receives • A dynamic equilibrium  Constantly changes but balances out! • High energy forms of radiation are transformed to lower energy forms such as infrared (sensible heat)

  9. Does Earth emit high energy radiation? (visible light or ultraviolet) NO!!

  10. B. Methods of Energy Transfer 1. Conduction: molecules collide with each other and vibrate • most efficient in solids • energy moves from warm to cold

  11. 2. Convection: movement of fluids (gas or liquid) that transfers energy • warmer = less dense  rises • cooler = more dense  sinks • energy moves from warm to cold

  12. • Diagram:

  13. • radiation can cause radiation! (it transforms into another type) 3. Radiation: PROCESS where energy travels in the form of electromagnetic waves

  14. Journal #31 1/6 Decide whether the following show Conduction, Convection, or Radiation… • The handle of a pan is hot • A warm object heats another without contact • Beach sand gets hot during the day • Cold air flows in when a window is opened • The upstairs floor is warmest • Sunlight makes pavement warm up • There is a breeze at the beach

  15. III. Energy Transformation A. Energy changes types frequently  Visible Light can become _____________. ? Infrared Energy

  16. based on position or state of an object B. Potential vs. Kinetic Energy 1. Potential Energy: • The energy an object could have (needs to be released)

  17. energy of movement 2. Kinetic Energy: • More speed and mass = more kinetic energy

  18. 3. Energy can be changed back and forth from kinetic to potential, but the Total Energy stays the same  Potential + Kinetic = SAME (always)

  19. Happy Winter Solstice • Shortest Day of the Year Sunrise: 7:22am Sunset: 4:25pm (least hours of insolation) • 9 Hours 3 Minutes of Daylight • Beginning of Winter Season • North Pole tilted away from Sun • Areas within Arctic Circle receive 24 hours of darkness • Sun Directly overhead at Tropic of Capricorn (23.5° South)

  20. Thermal Energy IV. A. Energy increases molecular movement • >molecular movement  >kinetic energy • leads to friction and heat of substance! B. Joules: unit of thermal energy

  21. • Units: °C °F K C. Temperature: the measure of kinetic energy of molecules!

  22. • What type of relationship is illustrated between these variables? As the Kinetic Energy of Molecules increases, the temperature increases  Type of relationship: direct

  23. • Converting temperatures the “easy way” • Converting from Celsius to Kelvin: Use a chart or Google!

  24. D. Specific Heat: the resistance that a material has to the absorption and release of heat 1. Also: the exact amount of energy required to raise the temperature of 1 gram of any material by 1oC

  25. 2. High Specific Heat  requires LOTS of energy to warm up  takes time to warm up & cool down What substance has the highest specific heat? WATER !!

  26. 3. How can we find specific heats of different materials? •Look it up:

  27. Q = Thermal Energy C = Specific Heat Capacity m = Mass ΔT = Change in Temperature 4. Equation: 5. Units:

  28. 4. Units for Specific Heat:  Joules per gram times degrees Celsius  (J/g •°C)  all other materials have LOWER specific heats than liquid water!

  29. 5. Since land heats up and cools off much faster than water, the Earth is heated unevenly  Land has a LOWER specific heat than water

  30. Different materials absorb and re-release energy from the Sun at different rates - leads to uneven heating!

  31. Which materials are absorbing more energy and which materials are reflecting more energy?

  32. Journal #32 1/7 Solve the equation for the following: • Mass • Specific Heat • Change in Temperature • How much thermal energy is required to raise 100 grams of water (C=4.18 J/g°C) by 25°C? • How much thermal energy is RELEASED if the same amount of water drops by 25°C?

  33. V. Energy of Phase Changes (Changes in the state of matter!) A. Melting or Liquification: matter changes from solid to liquid • energy is gained by the material (Low)

  34. B. Evaporation or Vaporization: matter changes from liquid to gas (vapor) • energy is gained by the material (Med) • evaporation occurs faster at higher temperatures Vaporize! • Boiling Point: when a material evaporates or vaporizes at the highest rate

  35. C. Sublimation: solid turns directly to gas (vapor), skipping the liquid phase Dry Ice (High) • energy is gained by the material • takes LOTS of energy to initiate sublimation (energy to melt + energy to vaporize)

  36. D. Condensation: matter changes from a gas (vapor) to a liquid (Med) • energy is lost by the material • when water condenses, it is called dew, mist, fog, or clouds

  37. E. Solidification or Freezing: matter changes from liquid to solid (Low) • energy is lost from the material • Crystallization: arrangement of solid molecules in a definite pattern

  38. solidification of molten rock (magma or lava) • Lithification:

  39. F. Deposition: gas or vapor turns directly into a solid, skipping the liquid phase in between • energy is lost by the material (High) • occurs when there is lots of vapor and a large temperature difference between two materials

  40. Certain Mornings…Deposition is everywhere!!!

  41. • Close Up

  42. energy released or absorbed during a phase change G. Latent Heat:

  43.  Energy gained during melting 1. Latent Heat of Fusion: (Lf) 2. Latent Heat of Vaporization: (Lv) 3. Latent Heat of Condensation: (Lc) Energy lost during freezing Energy gained during evaporation Energy lost during condensation

  44. 4. Latent Heats for Water:

  45. H. Ideal Phase Change Graph for H2O

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