1. Thermal Physics

2. 3 key terms Heat – Energy in transit. The energy transferred between objects because of a difference in temperature. Temperature – A measure of the average Kinetic Energy of the particles in a substance. Internal Energy – The energy of a substance due to the random motions of its component particles and the equal to the total energy of those particles.

3. Temperature We often associate temperature with how hot or cold something feels We often associate temperature with how hot or cold something feels Hot and Cold are terms that can be misleading Hot and Cold are terms that can be misleading The same object can feel warm or cool depending on the properties of the object and the condition of your body The same object can feel warm or cool depending on the properties of the object and the condition of your body

4. Hot Cold Luke warm

5. Moving Energy Changes Temp. Heat Consider an oven- turn the dial on and heat is delivered as energy flows. When the dial is off, energy stops flowing and temperature cools Consider an oven- turn the dial on and heat is delivered as energy flows. When the dial is off, energy stops flowing and temperature cools

6. Temperature Temperature is proportional to the Kinetic Energy of atoms and molecules. Temperature is proportional to the Kinetic Energy of atoms and molecules. To understand temperature, think of atoms & molecules and how they move. With more heat, atoms move more, have more KE. When heat is removed, the energy of theses moving atoms/ molecules is called internal energy. To understand temperature, think of atoms & molecules and how they move. With more heat, atoms move more, have more KE. When heat is removed, the energy of theses moving atoms/ molecules is called internal energy.

7. Internal Energy The energy of substance due to the random motions of its component particles and equal to the total energy of those particles The energy of substance due to the random motions of its component particles and equal to the total energy of those particles

8. ??????????????????????????? Why does a 1200 o C sparkle not hurt you, but a 200 o C stove burner will give you a nasty burn? A plasma torch in a welding shop has temperatures hotter than the Sun’s surface, why aren’t welders vaporized? What has more energy; a cup of boiling hot water or Lake Conroe in the winter time?

9. Thermal Equilibrium The state in which two bodies in physical contact with each other have identical temperatures The state in which two bodies in physical contact with each other have identical temperatures COLDWATER Warm Beverage In time both liquids will have equal temperatures

10. You can not find temperature until thermal equilibrium is reached You can not find temperature until thermal equilibrium is reached The temperature of the liquid in the thermometer must balance the temperature of the object being measured. This must happen in order to know the temperature The temperature of the liquid in the thermometer must balance the temperature of the object being measured. This must happen in order to know the temperature “You don’t read a thermometer until the mercury/ alcohol has stopped rising/ falling” “You don’t read a thermometer until the mercury/ alcohol has stopped rising/ falling”

11. Thermal Expansion Things get HOT they EXPAND Things get HOT they EXPAND Things get COLD they CONTRACT Things get COLD they CONTRACT – Concrete bridges – Rail Road Rails – Power Lines – Hot glass – cold water – cracks This is True for all solids, liquids and gasses (some more than others) This is True for all solids, liquids and gasses (some more than others)

12. Anomaly of Water A strange thing happens to water between 0°- 4°C: as it gets colder, it EXPANDS- GOOD NEWS FOR FISH!! A strange thing happens to water between 0°- 4°C: as it gets colder, it EXPANDS- GOOD NEWS FOR FISH!!

13. ICE 0°C 1°1°1°1° 2°2°2°2° 3°3°3°3° 4°4°4°4°

14. Thermometers A glass tube containing a thin column of mercury, colored alcohol, or colored mineral spirits A glass tube containing a thin column of mercury, colored alcohol, or colored mineral spirits When heated, Liquid Expands When heated, Liquid Expands

15. To calibrate thermometers and to set a standard for temperature we have chosen water to be our bench mark.- Not just any water – Pure Water at 1ATM of Pressure To calibrate thermometers and to set a standard for temperature we have chosen water to be our bench mark.- Not just any water – Pure Water at 1ATM of Pressure Calibrating Thermometers

16. What About Fahrenheit? We must convert with the following formulas: We must convert with the following formulas: – To find °F °F = (9/5(°C)) + 32 – To Find °C °C = 5/9(°F - 32)

17. With °F and °C, often times you get negative numbers; This is because many things are colder than our standard “ice” With °F and °C, often times you get negative numbers; This is because many things are colder than our standard “ice” To eliminate neg. values for temperature, the Kelvin Scale was used To eliminate neg. values for temperature, the Kelvin Scale was used – 0 Kelvin is as cold as anything can get – From 0 K, you can only go up Kelvin Scale

18. The best thermal lab on record has reached 0.0000001 K The best thermal lab on record has reached 0.0000001 K At 0K, the theory states that atoms would cease to vibrate, liquids would contract no more. At 0K, the theory states that atoms would cease to vibrate, liquids would contract no more.

19. Kelvin Conversions To find K Kelvin temp = °C + 273.15 To find K Kelvin temp = °C + 273.15 To find °C °C = Kelvin Temp - 273.15 To find °C °C = Kelvin Temp - 273.15 Practice Problems 10A 1-5 pg 363 HOMEWORK 2, 4, 5, 7, 9, 10 pg.387

20. ??????????????????????????? A piece of iron has a temperature of 10 0 C. A second identical piece of iron in twice as hot. What is the temperature of the second piece of iron? 10+273=283K 283x2 = 566K 566 – 273 = 293 o C

21. Section 10-2 Defining Heat Defining HeatReadandUnderstand p. 365-367

22. Defining Heat Heat: – Flow of energy – Moves in one direction, from hot to cold – Symbol Q – Has units for energy (Joule) (calorie, kilocalorie, dietary calorie, Btu, therm)

23. Mechanical Energy is Equal to Heat Energy KE=PE=work=Q=heat Doing work on a substance will cause it to heat up.

25. Specific Heat Capacity This is the amount of energy required to change the temperature of 1kg of a substance by 1 °C This is the amount of energy required to change the temperature of 1kg of a substance by 1 °C C p = Q/ m Δ T Q = m C P Δ T Q = Heat (Joules) m = mass (Kg) C p = Specific Heat (J/Kg°C) Δ T = change in temp (°C)

26. Table 10.4 pg 372 Substances take differing amounts of energy to heat up Substances take differing amounts of energy to heat up – Water heats up Slowly – Lead heats up fast

27. Calorimetry To determine specific heat capacity we do calorimetry To determine specific heat capacity we do calorimetry For calorimetry always remember: For calorimetry always remember: Energy absorbed = Energy released Q water = Q x C Pw M w Δ T w = C px M x Δ T x

29. Practice Probs. p.378 1 & 2 10c Pg.374 7, 6, 5, 4 Homework:Pg.387-388 13, 14, 16, 21, 22, 28 p.375-376

30. Q T graphs Heat Temperature Graphs

31. Heat Flow Thermal Conduction: this is how heat flows through a substance. Some materials conduct heat well. others are very poor (insulators) Thermal Conduction: this is how heat flows through a substance. Some materials conduct heat well. others are very poor (insulators) Generally, metals are good conductors of heat. Asbestos, cork, ceramic, cardboard,& fiberglass are good insulators Generally, metals are good conductors of heat. Asbestos, cork, ceramic, cardboard,& fiberglass are good insulators

32. Heat Moves in 3 Ways Conduction: heat moving through 2 objects that touch each other Conduction: heat moving through 2 objects that touch each other Convection: heating by movement of fluids(liquids and gases). Involves displacement of cold matter by hot Convection: heating by movement of fluids(liquids and gases). Involves displacement of cold matter by hot

33. Heat Movement Cont… Radiation: electromagnetic rays carry heat from everything above 0 Kelvin in the form of waves. No medium is needed for this- occurs in the vacuum of space. Also, near a campfire Radiation: electromagnetic rays carry heat from everything above 0 Kelvin in the form of waves. No medium is needed for this- occurs in the vacuum of space. Also, near a campfire

34. Thermos Keeps hot things hot, cold things cold because it minimizes heat flow Keeps hot things hot, cold things cold because it minimizes heat flowOVERHEAD

35. – Eskimo- Parka – Arabian - Desert Dress Clothes & climate Clothes & climate

36. Laws of Thermodynamics Heat, Work, and Internal Energy Q is heat, W is Work, U is internal Energy System- A collection of matter within a clearly defined boundary across which no matter passes. Environment- Everything outside a system that can affect or be affected by the system’s behavior.

37. Defining Work in terms of Changing Volume W = Fd Work = force x distance moved p.404 insert formula proof Work = pressure x volume change

38. Pressure

39. p. 405 11A 1 and 2 1. A) 6.4x105 J B) -4.8x105 J 2. -167.5 J; Work is done on the gas because the volume change is negative

40. First Law of Thermodynamics This law is a statement of the Law of Conservation of Energy. Heat, Work, and the Change in Internal Energy can be calculated. U = Q – W U-change in internal Energy Q-energy transferred to or from a system as heat W-Energy transferred to or from a system as work

41. Page 409 Look at the roller coaster and the bar graphs below to see an example of this view of the Conservation of Energy.

42. Page 413 11B problems 1-3 33J -143 J; removed as heat 10,000J

43. Second Law of Thermodynamics The Universe and all systems are moving towards greater disorder. The Entropy of the Universe increases in all natural processes. Heat and entropy are related. Entropy increases because energy is transferred as heat to a system.

44. Entropy Entropy is a measure of a system’s disorder. Increasing disorder reduces the energy available for work. Greater disorder means there is less energy to do work.

45. Direction of Energy Always towards a state of disorganization In order to organize energy, more energy must be input. Clean room Salt pepper shaker Heat death of the Universe.

47. T Q