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Thermal Energy

Thermal Energy. Temperature THE AVERAGE KINETIC ENERGY OF AN OBJECT. Average motion energy Thermal Energy THE TOTAL KINETIC + POTENTIAL ENERGY IN AN OBJECT. Energy of stored bonds + motion. Temperature Reference Points Freezing Point of Water 0 °C or 32°F Boiling Point of Water

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Thermal Energy

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  1. Thermal Energy

  2. Temperature • THE AVERAGE KINETIC ENERGY OF AN OBJECT. • Average motion energy • Thermal Energy • THE TOTAL KINETIC + POTENTIAL ENERGY IN AN OBJECT. • Energy of stored bonds + motion

  3. Temperature Reference Points • Freezing Point of Water • 0 °C or 32°F • Boiling Point of Water • 100°C or 212°F

  4. Temperature Conversions 212 32 TK = Temperature in Kelvin TC = Temperature in °C TF = Temperature in °F Temperature (°F) 0 100 Temperature (°C)

  5. Temperature Conversions

  6. HEAT TRANSFER

  7. Which object has the greatest temperature? • Which object has the greatest average kinetic energy? • Which object has the greatest total kinetic energy? • Which object has the greatest Thermal Energy? • Which object, left on its own, in outer space, has the greatest heat? • Which object, connected to the table, has the greatest heat transfer? A. 97°C 50 mL B. 7°C 1 L C. -2°C 1000 kL D. None of these

  8. Heat HEAT = THERMAL ENERGY THAT IS TRANSFERRED FROM ONE OBJECT TO ANOTHER. HEAT ALWAYS FLOWS FROM THE HIGHER TEMPERATURE TO THE LOWER TEMPERATURE Touch the leg of your chair and the leg of your desk. Which one is colder?

  9. Pizza Capacity • Think and Explain? When I throw my pizza into the microwave to warm it up, it isn’t the same temperature throughout. Why?

  10. Heat Capacity All substances will change temperature as they gain thermal energy. HEAT CAPACITY = THE AMOUNT OF TEMPERATURE CHANGE TO A HEATED OBJECT DEPENDS ON THE OBJECT AND THE MASS.

  11. Modes of Heat Transfer • The three methods of Heat Transfer • CONDUCTION • CONVECTION • RADIATION

  12. Conduction • CONDUCTION = THERMAL ENERGY TRANSFERRED BY THE COLLOSIONS OF PARTICLES • CONDUCTION REQUIRES CONTACT • It is an exchange of energy between atoms and electrons by collisions • Less energetic particles gain energy during collisions with more energetic particles.

  13. Materials Listed are common materials. Better conductors have a higher thermal conductivity Demo - POOR CONDUCTOR = GOOD INSULATOR

  14. Conduction Examples • Why is the tile cold and the carpet feel warm? • Because the tile is a better conductor and it has a greater heat capacity

  15. Convection • What is convection? • THERMAL ENERGY TRANSFERRED BY A CURRENT OF FLUID • REQUIRES A FLUID(Gas/Liquid) • When the movement results from differences in density, it is called natural convection • When the movement is forced by a fan or a pump, it is called forced convection

  16. Convection Heating • An example of natural convection • Explain what is happening • Water Temp Demo

  17. Convection Current Example • What is the forced convection? • What is the natural convection?

  18. Weather – due to natural convection

  19. Radiation • RADIATION = THERMAL ENERGY TRANSFERRED BY ELECTROMAGNETIC WAVES • RADIATION DOES NOT REQUIRE CONTACT • All objects radiate (give off) energy continuously in the form of electromagnetic waves due to thermal vibrations of the molecules

  20. Thermal Expansion • When an object is heated, it’s particles speed up and spread apart, making the object expand. • Demo - • Uses: Cavities, Bridges, Sidewalks Lines • Downsides - potholes

  21. Radiation example • No physical contact is necessary • The electromagnetic waves carry the energy • The heat transfer cannot be accounted for by conduction or convection (thru space)

  22. States of Matter

  23. Phase Summary

  24. States of Matter Notes • These are found online at • http://prezi.com/_2quyv8zpnzq/notes-states-of-matter/ • (Look at these or you’ll be sorry).

  25. Crystalline Amorphous Freezing Definite Shape Sublimation = Dry Ice Least Kinetic energy Melting Deposition = Frost Definite Volume Molecules in motion Medium Kinetic energy Property of Viscosity No Definite Volume Highest Kinetic Energy No Definite Shape Fluid Condensation Vaporziation

  26. Phase Change Graphs

  27. Thermal Energy and Phase Changes 150 100 50 0 Gas Vaporization Condensation Temperature (°C) Liquid Melting Freezing Solid 0 1 2 3 4 5 Thermal Energy

  28. Phase Change Process (S & L) • Melting – THERMAL ENERGY IS USED TO BREAK BONDS • The bonds that hold molecules in vibrating lattice structure are breaking. • The Intermolecular Forces Lessen • Freezing – THERMAL ENERGY IS USED TO CREATE BONDS AND HOLD MOLECULES IN PLACE • The bonds that will hold molecules in position are forming • The Intermolecular Forces Increase • Melting Point – THE TEMPERATURE AT WHICH AN OBJECT EITHER MELTS OR FREEZES.

  29. Evaporation = Escape • Brant’s Maximum Security Penitentiary for Incarcerated Dress Code Violators and Others. • If the highest IQ’s escape, what happens to the average Penitentiary IQ. • Up • Down • Same

  30. VAPORIZATION (L – G) • EVAPORATION – A CHANGE IN PHASE FROM LIQUID TO GAS AT THE SURFACE. • This cools the remaining liquid! • BOILING – A CHANGE IN PHASE FROME LIQUID TO GAS BELOW THE SURFACE. • This cools the remaining liquid! • Boiling Point – THE TEMPERATURE THAT AN OBJECT VAPORIZES OR CONDENSES.

  31. Condensation (G  L) • CONDENSATION – A CHANGE OF PHASE FROM GAS TO LIQUID. • This is a WARMING PROCESS for the liquid. • Gas molecules strike surface of liquid and give up so much energy that they can’t stay in gaseous phase • Examples Droplets forming on mirror Droplets on glass of water

  32. Condensation = Captured • The smart kids sneak out of a convocation in the gym and join the prison of ISS. What happens to the average IQ of the prison? • Up • Down • Same

  33. Phase Changes with the Gizmo • The differences with this type of graph, and the basic phase change graph is that the time is the x-axis instead of changing thermal energy. • Hint: In these graphs Mr. Nuetzel had an initial setup, then didn’t change any of the settings after starting it.

  34. Phase Change GizmoWith this setup, what will happen to the temp. graph?

  35. Phase Change GizmoWith this setup, what will happen to the temp. graph?

  36. Phase Change GizmoWith this setup, what will happen to the temp. graph?

  37. Phase Change GizmoWith this setup, what will happen to the temp. graph?

  38. What’s the difference between these two graphs?

  39. What’s the difference between these two graphs?

  40. Phase Change GizmoWith this setup, what will happen to the temp. graph?

  41. Interpreting Graphs • Hint – Mr. Nuetzel didn’t keep the RATE of heat transfer constant in these graphs.

  42. What is happening in this graph?

  43. What is happening in this graph?

  44. What is the difference in these graphs?

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