1. Temperature and Heat Heat Temperature Internal Energy Measurement of Heat Specific Heat Thermal Expansion

2. Temperature & Heat Absolute Zero Video – Nova Heat Mixes Lab Antifreeze in the Summer Lab

3. Temperature The quantity that tells how hot or cold something is compared with a standard.

4. Temperature Temperature is a measure of the average kinetic energy of the molecules of a substance. A thermometer measures this KE as the molecules collide with the thermometer’s bulb.

5. Temperature Scales Freezing point to boiling point of water Fahrenheit: 32 to 212, range of 180 degrees. Celsius: 0 to 100, range of 100 degrees. Kelvin: 273 to 373, range of 100 degrees.

6. Kelvin Scale At constant pressure the volume of a gas changes by 1/273 of its volume at 0C o with each 1C o change in temperature. At -273 0C o the gas is reduced to 273/273 and the volume is 0.

7. Heat Some two hundred years ago heat was thought to be an invisible fluid called caloric, which flowed like water from hot objects to cold objects. Caloric appeared to be conserved – that is, it seemed to flow from one place to another without being created or destroyed. This idea was the forerunner of the law of conservation of energy.

8. Heat is Kinetic Energy During the French Revolution Count Von Rumford (Benjamin Thompson) was boring cannons for the Bavarian army and he notice: “I perceived, by putting my hand into the water and touching the outside of the cylinder that, Heat was generated; … at 2 hours and 30 minutes it (the water) ACTUALLY BOILED…without any fire.” The generation of heat was related to the kinetic energy of truing the cannon barrel.

9. Heat Heat is the net energy transferred from one object to another because of a temperature difference. Internal Energy Includes: molecular translation form place to place, molecular vibration, molecular rotate.

10. Heat versus temperature Temperature A measure of hotness or coldness of an object Based on average molecular kinetic energy Heat Based on total internal energy of molecules Doubling amount at same temperature doubles heat

11. Thermal Equilibrium When object on contact with each other reach the same temperature and heat no longer flows between them.

12. How do we measure temperature? Think about using a thermometer

13. How does the thermometer know how hot the substance is?

14. The molecules of the substance bump into the thermometer and transfer energy. How often and how hard they bump into the thermometer are directly related to their speed. Temperature turns out to be related to the average speed of the molecules in a substance.

15. Temperature is not a measure of the total amount of energy in an object. Thermal Energy = internal energy = a measure of the total kinetic and potential energy in an object

16. Measurement of Heat Heat is energy and thus has units of Joules. However, heat has a special unit of calorie. A calorie is the heat needed to raise one gram of water by 1C o. 1cal = 4.186J 1kcal = 1000 cals 1Cal (food calorie) = 1000 cals

17. Specific Heat Each substance has its own specific heat. The specific heat of any substance is the amount of heat it takes to raise 1kg of the substance by 1C o. Specific heat of water = 1.000 kcal/kgC o. H = mc  Where: m = mass c = specific heat  T = change in temperature.

18. Specific Heat Table

19. Thermal Expansion Why? The Bridge Connection Lab Concept Development - Thermal Expansion

20. Thermal Expansion

22. Bimetallic Strip Ball and ring Drinking Bird Soda Can (Yes, I can make it work!)

23. Expansion of Water This is a good thing. Water temp. vs. depth.

24. Yeah! Chapter Problems. Chapter 21: 2, 4, 5, 9, 10, 12, 13, 14, 15, 17, 19, 20, 23, 26, 28, 30, 31, 33 & 34.

25. Heat Transfer Conduction Convection Radiation Absorption of Radiant Energy Emission of Radiant Energy Newton’s Law of Cooling Global Warming / Greenhouse Effect

26. Solar Equality Lab Purpose: To determine the power output of the sun.

27. Heat Transfer Three mechanisms for heat transfer due to a temperature difference 1.Conduction 2.Convection 3.Radiation Natural flow is always from higher temperature regions to cooler ones

28. Conduction Conduction – Conductor – Insulator

29. Conduction Heat flowing through matter Mechanism –Hotter atoms collide with cooler ones, transferring some of their energy –Direct physical contact required; cannot occur in a vacuum Poor conductors = insulators (Styrofoam, wool, air…)

30. Sample conductivities MaterialRelative conductivity Silver0.97 Iron0.11 Water1.3x10 -3 Styrofoam1.0x10 -4 Air6.0x10 -5 Vacuum0

31. Convection Convection -

32. Convection Energy transfer through the bulk motion of hot material Examples –Space heater –Gas furnace (forced) Natural convection mechanism - “hot air rises”

33. Heat Transfer Convection in a House

34. Heat Transfer The Wind Sea BreezeLand Breeze

35. Convection Why does rising warm air cool?

36. Heat Transfer Convection on the Sun

37. Heat Transfer Thermos Bottle

38. Radiation

39. Radiant energy - energy associated with electromagnetic waves Can operate through a vacuum All objects emit and absorb radiation Temperature determines –Emission rate –Intensity of emitted light –Type of radiation given off Temperature determined by balance between rates of emission and absorption –Example: Global warming

40. Radiation Absorption of Radiant Energy – Emission of Radiant Energy – Con. Dev. 22-1 Transmission of Heat

41. Solar Energy Lab 56

42. Newton’s Law of Cooling

43. Global Warming What causes it?

44. Greenhouse Effect

45. Video An Inconvenient Truth

46. Yeah! More Problems Chapter 22: 1, 2, 3, 4, 7, 8, 9, 12, 16, 17, 19, 20, 21, 22, 24, 25, 26, 27 & 28.

47. Chapter 24 Thermodynamics: Laws of Thermodynamics Song: http://www.youtube.com/watch?v=KTHiIwxcexI

48. Thermodynamics The study of heat and its relationship to mechanical and other forms of energy Thermodynamic analysis includes –System –Surroundings (everything else) –Internal energy (the total internal potential and kinetic energy of the object in question) Energy conversion –Friction - converts mechanical energy into heat –Heat engines - devices converting heat into mechanical energy –Other applications: heat pumps, refrigerators, organisms, hurricanes, stars, black holes, …, virtually any system with energy inputs and outputs

49. Absolute Zero Define: Compared to Celsius:

50. Lab The Uncommon Cold - #63

51. Kinetic Theory & Gas Laws Temperature & Volume Charles’ Law Jacques Charles (1746-1823) The volume of a fixed amount of gas at constant pressure is directly proportional to its absolute (Kelvin) temperature. V = kT http://www.grc.nasa.gov/WWW/K-12/airplane/aglussac.html

52. 1 st Law of Thermodynamics Define Heat added =

53. The first law of thermodynamics Conservation of energy Components –Internal energy –Heat –Work Stated in terms of changes in internal energy Application: heat engines

54. Adiabatic Process Define:

55. Adiabatic Process Piston in engines:

56. 2 nd Law of Thermodynamics Define:

57. The second law of thermodynamics Equivalent statements: No process can solely convert a quantity of heat to work (heat engines) Heat never flows spontaneously from a cold object to a hot object (refrigerators) Natural processes tend toward a greater state of disorder (entropy)

58. Heat Engines Definition:

59. Heat Engines

60. Carnot (ideal) Efficiency Ideal Efficiency = Example:

61. Order Tends to Disorder Entropy: http://www.youtube.com/watch?v=5KIhDVLbMeY&feature=related

62. Entropy Things: Living systems: Useful energy:

63. More physics fun Chapter 24 # 1, 3, 4, 6, 11, 12, 31, 32 & 33. Chapter 24 # 13, 19, 21, 22, 23, 24, 37, 39 & 40.

64. Second law, third statement Real process = irreversible process Measure of disorder = entropy Second law, in these terms: The total entropy of the Universe continually increases Natural processes degrade coherent, useful energy –Available energy of the Universe diminishing –Eventually: “heat death” of the Universe Direction of natural processes – Toward more disorder –Spilled milk will never “unspill” back into the glass!

65. Kinetic Theory & Gas Laws Pressure & Number of Molecules Pressure is directly proportional to the number of gases molecules present. p  N

66. Kinetic Theory & Gas Laws Pressure & Temperature At constant volume pressure is directly proportional to the Kelvin temperature. p  T

67. Kinetic Theory & Gas Laws Pressure & Temperature A boiler explosion broke this locomotive into small pieces and sprayed them, and the crew, over a wide area of Florida. http://afu.com/steam/

68. Since we Mentioned Steam Engines Thomas and his prototype

69. Kinetic Theory & Gas Laws Pressure & Volume Boyle’s Law Robert Boyle (1627 – 1691) At constant temperature pressure is inversely proportional to the volume. p  1/V where V = volume. http://www.grc.nasa.gov/WWW/K-12/airplane/aboyle.html

70. Kinetic Theory & Gas Laws Ideal Gas Law Putting all three of these together the Ideal Gas Law is obtained. P  (NT)/V The proportionally can be used to take ratios for calculations. p 2 /p 1 = (V 1 /V 2 )(T 2 /T 1 ) assuming a constant number of molecules, N.

71. Kinetic Theory and Atoms John Dalton (1766 – 1844) All matter is composed of tiny particles. All atoms of each element are identical (he didn’t know about isotopes.) Atoms are not created or destroy in chemical reactions (conservation of matter.) Elements bond in whole ratios to form compounds. Chemical reactions are the union and separation of atoms.

72. Energy, heat, and molecular theory Two responses of matter to heat 1.Temperature increase within a given phase –Heat goes mostly into internal kinetic energy –Specific heat 2.Phase change at constant temperature –Related to changes in internal potential energy –Latent heat

73. Phase changes Solid/liquidLiquid/gasSolid/gas Latent heatFusionVaporizationSublimation Temperature (Direction ->) Melting pointBoiling pointSublimation Temperature (Direction <-) Freezing point Condensation point Sublimation

74. Evaporation and condensation Individual molecules can change phase any time Evaporation: –Energy required to overcome phase cohesion –Higher energy molecules near the surface can then escape Condensation: –Gas molecules near the surface lose KE to liquid molecules and merge

75. Phases of Matter Solid Molecules arranged in a rigid crystalline structure. Expansion occurs during heating because molecules vibrate with grater amplitude.

76. Phases of Matter Liquids Molecules not in a lattice. Molecules can vibrate and rotate. Molecules are still close together. Take the shape of container.

77. Phases of Matter Gas Molecules relatively far apart. Molecules have high speed of Kinetic Energy.

78. Latent Heat Heat associated with a phase change. L f = latent heat of fusion H = m L f = heat needed to melt a substance. L v = latent heat of vaporization H = m L v = heat needed to vaporize a substance.

79. Latent Heat Latent heat of fusion used to break apart the crystalline lattice of water.

80. Latent Heat Graph