1. HEAT
TEMPERATURE

2. WHAT YOU SHOULD KNOW
A WARMER OBJECT CAN WARM A COOLER OBJECT BY CONTACT OR FROM A DISTANCE.

3. SOME MATERIALS CONDUCT HEAT BETTER THAN OTHERS.

4. HEAT IS TRANSFERRED BY THE COLLISION OF ATOMS AGAINST ONE ANOTHER.

5. HEAT FLOWS FROM WARMER OBJECTS TO COOLER OBJECTS UNTIL BOTH REACH THE SAME TEMPERATURE.

6. REMEMBER…. WORK IS FORCE X DISPLACEMENT
KINETIC ENERGY IS ENERGY OF MOTION
POTENTIAL ENERGY IS ENERGY OF POSITION

7. LAW OF CONSERVATION OF MECHANICAL ENERGY
CONSERVATION OF MECHANICAL ENERGY …IN THE ABSENCE OF FRICTION, THE TOTAL MECHANICAL ENERGY OF THE SYSTEM STAYS THE SAME.

8. TEMPERATURE MEASURE OF THE AVERAGE KINETIC ENERGY IN THE OBJECT.
TELLS US HOW COLD OR HOT SOMETHING IS BY COMPARISON TO AN ESTABLISHED STANDARD OR SCALE.

9. TEMPERATURE SCALES KELVIN – ABSOLUTE SCALE
FAHRENHEIT – USED IN THE U. S.
CELSIUS – USED IN COUNTRIES THAT HAVE ADOPTED THE METRIC SYSTEM AND THE SCIENTIFIC COMMUNITY

10. WATER
WATER EXPANDS WHEN COOLED TO FREEZING BECAUSE IT FORMS OPEN STRUCTURES AS IT CHANGES STATE.
4 DEGREE WATER IS THE DENSEST WATER THERE IS.

11. HOW DO THERMOMETERS WORK
ALL SUBSTANCES EXPAND WHEN HEATED.
A SEALED COLUMN WITH A LIQUID IN A VACCUM. AS THE LIQUID GAINS OR LOOSES ENERGY IT EXPANDS OR CONTRACTS IN THE TUBE AGAINS THE SCALE AND WE READ THE TEMPERATURE.

12. TEMPERATURE SCALES
CELSIUS SCALE
FAHRENHEIT SCALE
KELVIN

13. CELSIUS ZERO DEGREES – FREEZING 100 DEGREES – BOILING
THE GAP BETWEEN IS DIVIDED INTO 100 EQUAL PARTS CALLED DEGREES.
NAMED IN HONOR OF SWEDISH ASTRONOMER ANDERS CELSIUS.

14. FAHRENHEIT SCALE 32 DEGREES – FREEZING 212 DEGREES – BOILING
scale based on 32° for the freezing point of water and 212° for the boiling point of water, the interval between the two being divided into 180 equal parts.

15. The 18th-century German physicist Daniel Gabriel Fahrenheit
his scale was built on the Rømer’s scale, the two fixed reference points are that brine also freezes at 0 degrees and water boils at 60 degrees. He observed that, on this scale, water freezes at 7.5 degrees. Fahrenheit multiplied each value by four in order to eliminate fractions and increase the granularity of the scale (resulting in 30 and 240 degrees, respectively). He then re-calibrated his scale between the freezing point of water and normal human body temperature (which he observed to be 96 degrees); he adjusted the scale so that the melting point of ice would be 32 degrees, so that 64 intervals would separate the two, allowing him to mark degree lines on his instruments by simply bisecting the interval six times (since 64 is 2 to the sixth power).[

16. KELVIN
ZERO IS THE LOWEST POSSIBLE SCALE CALLED ABSOLUTE ZERO. THE TEMPERATURE AT WHICH ALL ATOMIC MOTION CEASES. THIS IS THE SAME TEMPERATURE AS DEGREE CELSIUS.
NAMED IN HONOR OF BRITISH PHYSICIST LORD KELVIN.

17. TEMPERATURE CONVERSION EQUATION
°C = 5/9(°F – 32)
°F = 9/5 °C + 32
K = °C

18. TEMP AND ENERGY THE MORE KINETIC ENERGY THE GREATER THE TEMPERATURE
THE WARMTH YOU FEEL WHEN YOU TOUCH SOMETHING HOT IS KINETIC ENERGY TRANSFERING TO YOUR HAND.

19. 1 LITER OF WATER VS 2 LITERS OF WATER
HOW DOES THE TEMPERATURE OF THE TWO CONTAINERS OF WATER COMPARE?
HOW DOES THE AMOUNT OF KINETIC ENERGY OF THE TWO CONTAINERS OF WATER COMPARE?

20. HEAT
THE ENERGY THAT TRANSFERS FROM ONE OBJECT TO ANOTHER BECAUSE OF A TEMPERATURE DIFFERENCE BETWEEN THEM IS CALLED HEAT.

21. MATTER AND HEAT MATTER DOES NOT CONTAIN HEAT…IT CONTAINS ENERGY.
HEAT IS TRANSFER OF ENERGY.
ONCE IT IS TRANSFERRED IT IS NO LONGER HEAT.

22. HOW DOES HEAT FLOW?
HEAT FLOWS FROM HOT TO COLD.

23. THERMAL EQUILIBRIUM
WHEN NO HEAT FLOWS BETWEEN OBJECTS THEY ARE IN THERMAL EQUILIBRIUM.

24. INTERNAL ENERGY
THE TOTAL OF ALL ENERGIES WITHIN A SUBSTANCE.

25. COMPONENTS OF INTERNAL ENERGY
TRANSLATIONAL KINETIC ENERGY – JOSTLING MOLECUES
ROTATIONAL KINETIC ENERGY – MOLECULES SPINNING
POTENTIAL ENERGY – DUE TO FORCES BETWEEN MOLECULES

26. TOTAL INTERNAL ENERGY
TRANSLATIONAL KINETIC ENERGY + ROTATIONAL KINETIC ENERGY + POTENTIAL ENERGY = INTERNAL ENERGY
ANY OF THESE ENERGIES MAY CHANGE WHEN A SUBSTANCE GIVE OFF OR TAKES IN HEAT.

27. FORMULA INTERNAL ENERGY = PE + KE
CHANGE IN PE + CHANGE KE + CHANGE IN INTERNAL ENERGY = 0

28. MEASURING HEAT
calorie – THE AMOUNT OF HEAT REQUIRED TO RAISE THE TEMPERATURE OF 1 GRAM OF WATER BY 1 °C

29. calorie VS CALORIE calorie IS THE OFFICIAL SI UNIT.
CALORIE IS 1000 calories.
CALORIE IS THE CALORIE USED FOR FOOD. IF AN ITEM HAS 200 CALORIES THAT MEANS IT HAS 200,000 calories OF ENERGY.

30. Heat As Energy Transfer
If heat is a form of energy, it ought to be possible to equate it to other forms. The experiment below found the mechanical equivalent of heat by using the falling weight to heat the water:
4.184 Joules = 1 calorie
4184 Joules = 1 CALORIE

31. CONVERSION OF calories TO JOULES
1 calorie = J
1 CALORIE = 4184 J
HOW DO WE DETERMINE THE ENERGY VALUE IN FOOD?
WE BURN THE FOOD AND MEASURE THE ENERGY RELEASED AS HEAT.

32. Calorimetry – Solving Problems
Closed system: no mass enters or leaves, but energy may be exchanged
Open system: mass may transfer as well
Isolated system: closed system where no energy in any form is transferred
For an isolated system,
Energy out of one part = energy into another part
Or: heat lost = heat gained

33. Calorimetry – Solving Problems
For an isolated system,
Energy out of one part = energy into another part
Or: heat lost = heat gained
Qout = Qin
mc(ti–tf) = mc(tf-ti)
HINT: Always subtract the lower temperature from the higher temperature!
C- specific heat capacity
M – mass
Ti – initial temperature
Tf- finial temperature

34. Calorimetry – Solving Problems
The instrument to the left is a calorimeter, which makes quantitative measurements of heat exchange. A sample is heated to a well-measured high temperature, plunged into the water, and the equilibrium temperature measured. This gives the specific heat of the sample.

35. Calorimetry – Solving Problems
Another type of calorimeter is called a bomb calorimeter; it measures the thermal energy released when a substance burns.
This is the way the Caloric content of foods is measured.

36. PROBLEM
A WOMAN WITH AN AVERAGE DIET CONSUMES AND EXPENDS ABOUT 2000 CALORIES PER DAY. THE ENERGY USED BY HER BODY IS EVENTUALLY GIVEN OFF AS HEAT. HOW MANY JOULES PER SECOND DOES HER BODY GIVE OFF? OR, IN OTHER WORDS, WHAT IS HER AVERAGE THERMAL POWER OUTPUT?

37. ANSWER
2000 CAL. 1 HOUR J
24 HOUR S CAL.
96.89 JOULES

38. QUESTION
SUPPOSE YOU USE A FLAME TO ADD A CERTAIN QUANTITY OF HEAT TO 1 LITER OF WATER, AND THE WATER TEMPERATURE RISES BY 2 °C. IF YOU ADD THE SAME QUANTITY OF HEAT TO 2 LITERS OF WATER, BY HOW MUCH WILL ITS TEMPERATURE RISE?

39. ANSWER
1 °C
WHY?
BECAUSE THE DOUBLED VOLUME HALVES THE TEMPERATURE INCREASE.

40. SPECIFIC HEAT CAPACITY
SOME OBJECTS REMAIN HOT LONGER THAN OTHER OBJECTS BECAUSE THEY CAN STORE MORE HEAT THAN OTHER OBJECTS.
A MEASURE OF THE AMOUNT OF HEAT NEEDED TO RAISE THE TEMPERATURE OF 1 KG OF A SUBSTANCE BY 1°C

41. SPECIFIC HEAT SI UNIT – J/Kg°C
CHANGE IN HEAT = MASS X SPECIFIC HEAT X CHANGE IN TEMP.
∆Q = mc ∆T
c IS THE SPECIFIC HEAT

42. Specific Heat
Specific heats of gases are more complicated, and are generally measured at constant pressure (cP) or constant volume (cV).
Some sample values:

43. CONSERVATION OF ENERGY
HEAT LOST = HEAT GAINED
mc ∆T = mc ∆T
c OF WATER IS 4186 J/Kg°C
c OF ICE IS 2090 J/Kg°C

44. THERMAL EXPANSION
DIFFERENT SUBSTANCES EXPAND AT DIFFERENT RATES AND THEIR EXPANSION IS DIRECTLY RELATED TO THE AMOUNT OF KINETIC ENERGY IN THE SUBSTANCE.

45. LINEAR EXPANSION
WHEN A SOLID OBJECT EXPERIENCES A TEMPERTURE CHANGE, ITS LENGTH WILL INCREASE BY A CERTAIN AMOUNT DEPENDING UPON THE NATURE OF THE MATERIAL.

46. EQUATION
CHANGE IN LENGTH = ORIGINAL LENGTH X COEFFICIENT OF EXPANSION X CHANGE IN TEMPERATURE
∆L = Loα∆T

47. COEFFICIENT OF LINEAR EXPANSION
A CHARACTERISTIC PROPERTY OF A PARTICULAR MATERIAL THAT TELL YOU HOW READILY A MATERIAL EXPANDS.
SI UNIT IS 1/°C OR °C-1

48. AREA EXPANSION AN OBJECT MAY ALSO EXPAND IN AREA WHEN HEATED.
CHANGE IN AREA = 2 X ORIGINAL AREA X COEFFICIENT OF EXPANSION X CHANGE IN TEMP.
∆A = 2Aoα∆T

49. VOLUME EXPANSION
CHANGE IN VOLUME = ORIGINAL VOLUME X COEFFICIENT OF VOLUME EXPANSION X CHANGE IN TEMP.
∆V = Voβ∆T
Β IS THE COEFFICIENT OF VOLUME EXPANSION

50. QUESTIONS HOW DO WE APPLY THIS INFORMATION IN A THERMOSTAT?
…TO A BRIDGE?
…TO OPENING A JAR?

51. PROBLEM
FOR DIFFERENT LENGTH OF STEEL, EXPANSION WOULD FOLLOW THE SAME PROPORTION. FOR SHORT LENGTH OF STEEL, EXPANSION MAY BE NEGLIGIBLE. BUT CONSIDER THE EXPANSION FOR A SNUGLY FITTING STEEL PIPE THAT COMPLETELY ENCIRCLES THE EARTH. HOW MUCH LONG ER WOULD THIS 40 MILLION METER PIPE BE IF ITS TEMPERATURE INCREASED BY 1°C
(STEEL CHANGES 1 PART IN FOR EACH °C
CHANGE IN TEMP.

52. ANSWER
= X
1 X X 106
X = 40 METERS

53. TEMPERATURE INCREASE
WHEN TEMPERATURE INCREASES IT IS A CHANGE IN THE TRANSLATIONAL ENERGY ONLY.

54. LATENT HEAT
THE AMOUNT OF ENERGY THAT IS NEEDED TO CAUSE A CHANGE IN PHASE.
Q = MASS X LATENT HEAT
LATENT HEAT WILL BE HEAT OF VAPORIZATION OR HEAT OF FUSION.

55. HEAT OF FUSION
THE QUNATITY OF HEAT NEEDED PER KILOGRAM TO MELT A SOLID AT A CONSTANT TEMPERATURE AND ATMOSPHERIC PRESSURE.
CHANGE IN HEAT = MASS X HEAT OF FUSION
∆Q = mhf
SI UNIT – J/Kg

56. HEAT OF FUSION WATER HEAT OF FUSION IS 3.35 X 105 J/Kg.
THAT IS THE AMOUNT OF HEAT 1 KG OF ICE MUST ABSORB IN ORDER TO TURN TO WATER.

57. HEAT OF VAPORIZATION
THE QUANTITY OF HEAT NEEDED PER KILOGRAM TO VAPORIZE A LIQUID AT A CONSTANT TEMPERATURE AND ATMOSPHERIC PRESSURE.
CHANGE IN HEAT = MASS X HEAT OF VAPORIZATION
∆Q = mhV

58. HEAT OF VAPORIZATION WATER
2.26 X 106 J/Kg
THIS IS THE AMOUNT OF HEAT THAT 1 KG OF WATER MUST ABSORB TO CHANGE TO WATER VAPOR.

59. PROBLEM
SUPPOSE WE KNOW THE NUMBER OF CALORIES NEEDED TO RAISE THE TEMPERATURE OF 1 LITER OF WATER BY 15°C. THE SPECIFIC HEAT CAPACITY FOR WATER, c, IS 1 cal/g°C, AND THE MASS OF 1 LITER OF WATE IS 1 KILOGRAM, WHICH IS 1000 GRAMS. REMEMBER 1 GRAM OF WATER HAS VOLUME OF 1mL. HOW MUCH ENERGY IS USED?

60. ANSWER Q = mc ∆T Q = 1000G X 1 cal/g°C X 15°C Q = 15000 calories
15000 X = J
SUPPOSE WE DELIVER THIS ENERGY TO THE WATER WITH A 1000 WATT BURNER. HOW LONG WILL IT TAKE TO HEAT THE WATER.

61. ANSWER
WE KNOW THAT 1000 WATTS DELIVERS ENERGY AT THE RATE OF 1000 JOULES PER SECOND.
ENERGY = POWER X TIME
62760 J = 1000 W/S X T
62.76 S = T

62. WATER
BECAUSE WATER HAS SUCH A HIGH SPECIFIC HEAT CAPACITY, IT CAN ABSORB A GREAT AMOUNT OF ENERGY. THIS MAKES IT A WONDERFUL COOLING AGENT.

63. STEAM V.S. WATER VAPOR
WATER VAPOR IS AN INVISIBLE GAS THAT RESULTS WHEN WATER BOILS OR EVAPORATES
STEAM IS WHAT YOU SEE WHEN WATER VAPOR IS COOLED AND CONDENSES BACK INTO WATER DROPLETS.

64. EXAMPLE
AN IGLOO IS MADE OF 224 BLOCKS OF ICE AT 0 °C, EACH WITH A MASS OF 12.0 KG. HOW MUCH HEAT MUST BE GAINED BY THE ICE TO MELT THE ENTIRE IGLOO?

65. SOLUTION M = 2690 KG hf= 3.35 x 105 J/kg ∆Q = mhf
∆Q = 2690 X 3.35 x 105 J/kg
∆Q = 9.01 X 108 J

66. EXTENSION
HOW MUCH HEAT IS NECESSARY FOR THE IGLOO TO INCREASE ITS TEMPERATURE BY 2 °C?
Q = mc∆T
Q = 2690 X 4187 X 2 °C
Q = 2.3 X 107 J

67. FURTHER
WHAT WAS THE TOTAL ENERGY NEEDED TO CHANGE THE TEMPERATURE 2 °C AND MELT THE ICE?
QT= ∆Q + Q
QT= 9.01 X 108 J+ 2.3 X 107 J
QT= 11.3 X 107 J

68. TYPES OF HEAT TRANSFER
CONDUCTION
CONVECTION
RADIATION

69. CONDUCTION
THE TRANSFER OF HEAT ENERGY THROUGH CONTACT OF ATOMS AND MOLECULES AGAINST OTHER ATOMS AND MOLECULES.
CONDUCTORS-MATERIALS THAT TRANSFER HEAT WELL.
METALS ARE GOOD CONDUCTORS.
INSULATORS – MATERIALS THAT DO NOT TRANSFER HEAT WELL.
STYROFOAM IS A GOOD INSULATOR

70. CONVECTION
THE TRANSFER OF HEAT BY THE MOVEMENT OF THE HOTTER SUBSTANCE THROUGH A COLDER SUBSTANCE.
CONVECTION CURRENTS IN THE ATMOSPHERE PRODUCE WINDS.
UNEVEN HEATING OF THE AIR CAUSES CONVECTION CURRENTS.
WHY CAN YOU HOLD YOUR FINGERS BESIDE A CANDLE FLAME BUT NOT ABOVE IT?

71. RADIATION RADIANT ENERGY IS ANY ENERGY TRANSMITTED BY RADIATION
IN RADIATION THE ENERGY MOVES AND NOT THE SUBSTANCE.
RADIANT ENERGY DOES NOT NEED A MEDIUM.

72. RADIANT ENERGY
ALL OBJECTS CONTINUALLY EMIT RADIANT ENERGY IN A MIXTURE OF WAVELENGTHS.
LOW TEMP = LONG WAVELENGTHS
HIGH TEMP = SHORT WAVELENGTHS
IF IT IS HOT ENOUGH THE WAVELENGTH WILL BE SHORT ENOUGH TO BE IN THE VISIBLE LIGHT RANGE. …WHITE HOT OR RED HOT

73. WHAT HAPPENS TO THE ENERGY
REFLECTED OR ABSORBED
IF IT IS ABSORBED IT WILL INCREASE THE INTERNAL ENERGY OF THE OBJECT DOING THE ABSORBING.

74. ABSORPTION VS REFLECTION
A GOOD ABSORBER IS A BAD REFLECTOR AND VICE VERSA.
EX: THE PUPIL OF THE EYE – GREAT ABSORBER, BUT THE RETINA OF THE EYE IS A BAD ABSORBER. HOW DO WE KNOW THIS?

75. ABSORPTION V.S. EMISSION
A GOOD ABSORBER IS A GOOD EMITTER.
EX: ANTENNA RECEIVE AND TRANSMIT
BLACK OBJECTS ABSORB HEAT BUT GIVE IT OFF EASILY TO REACH EQUILIBRIUM
EARTH IS AN ABSORBER DURING THE DAY AND AN EMITTER AT NIGHT

76. NEWTON’S LAW OF COOLING
RATE OF COOLING IS PROPORTIONAL TO THE CHANGE IN TEMPERATURE

77. GREEN HOUSE EFFECT
EARTH’S TEMP. DEPENDS ON THE ENERGY BALANCE BETWEEN INCOMING SOLAR RADIATION AND OUTGOING TERRESTRIAL RADIATION.
WHEN THE ATMOSPHERE IS NOT TRANSPARENT ENOUGH TO ALLOW THE OUTGOING RADIATION TO LEAVE, A BUILD UP OF HEAT RESULTS.

78. EARTH’S TEMP.
THE BUILD UP OF HEAT CAUSES THE EARTH’S TEMP. TO RISE, ICE CAPS & GLACIERS TO MELT, AND WEATHER PATTERNS TO CHANGE.
LAST 500,000 YEARS – DEGREES
OVER HEATING EARTH TODAY MAY CAUSE THE NEXT ICE AGE
HIGHER TEMP > WARMER OCEANS > INCREASED EVAPORATION > INCREASED SNOWFALL IN POLAR REGIONS > LOWER PLANET TEMPS > ICE AGE