1. Overview of Physics 102 Structure: Phys 101 not needed for this class
Focus on concepts
Lecture/lab format
Interactive: experiment and observation
Exams:
3 midterms, 1 comprehensive final
Lowest exam score dropped
Chance to make up some points through exam review
Homework:
Reading questions: due online day before class
Problems from book: due the class period after we finish chapter
overview

2. Tentative schedule Chapter 15: Temperature, heat and expansion
Chapter 16: Heat transfer
Chapter 17: Change of phase
Chapter 18: Thermodynamics
Midterm 1
Chapter 19: Vibrations and waves
Chapter 20: Sound
Chapter 21: Musical sound
Midterm 2
Chapter 22: Electrostatics
Chapter 23: Electric current
Chapter 24: Magnetism
Midterm 3
Chapter 25: Induction
Final exam

3. Activities Do “Initial Ideas on Heat and Thermodynamics”
Do “Initial Questions about temperature, heat, entropy, thermal energy”
Do Assignment 1
(see PH 102 folder on G drive)

4. Perspective on heat and thermodynamics
(see Course Outline page 5)
Aspects of motion
Consequences of vast numbers of constituent parts
Instead of keeping track of the trajectory of each atom, a substance can be described in terms of macroscopic properties such as temperature, pressure and volume.
Three basic concepts to define and differentiate:
Thermal energy
Temperature
Heat

5. Thermal Energy Microscopic view Macroscopic view
Potential Energy contribution
Kinetic Energy contribution
Macroscopic view
As part of internal energy
Thermal energy ≠ temperature
Examples

6. Temperature Microscopic view Macroscopic view Temperature scales
Proportional to average random translational kinetic energy per particle (absolute, e.g. Kelvin)
Macroscopic view
There is a qualitative notion of hot and cold, which we measure with temperature
Temperature scales
History
Definitions °C, °F, K
Thermometers
Do: Predictions/Notes Kinetic Theory of Gases,
Simulation:

7. Thermal expansion Material expansion due to temperature increase
Reasons for
Mathematical definition
Examples
Bimetallic strips
Metal rods
Holes (recall Assignment 1)
Exceptions
H20
Long chain molecules

8. Heat
Definition: energy transfer by virtue of a temperature difference between units
Heat ≠ Temperature
Specific heat
Heat exchange and existence of specific heat
Reasons for differences in specific heats
High specific heat of H2O
Specific heat related phenomena
Weather
Common experiences
Heat ≠ thermal energy
Do “specific heat” lab
Examples

9. Energy units Heat energy is traditionally defined in calories.
1 cal = heat needed to raise the temperature of 1 gram of water by 1°C.
1 Cal = 1000 cal
If you capitalize calorie, it means something different. These are called food Calories. You need to eat about 2000 Calories per day.
Work is defined in physics as energy required to move a massive object or substance. Work is traditionally measured in Joules.
1 J = work done in moving 1 meter against a force of 1 Newton
Heat and work are both forms of energy, and we can measure both in Joules.
1 cal = 4.2 J

11. Kinds of motion
There are a lot of ways molecules can move. They can change their positions (translation). They can also rotate, vibrate, twist and move in other complicated ways. Temperature involves translation only. When molecules are moving faster on average, the temperature is higher. It is an intensive property - it does not depend on the amount of the substance involved. Internal energy involves all kinds of motion of molecules, including rotation, etc. It is an extensive property - it does depend on the amount of the substance involved.

12. Temperature vs. Thermal Energy
Temperature does not measure the total thermal energy of a substance. A swimming pool and a goldfish bowl can be the same temperature but the swimming pool has much more thermal energy. In both cases, the total thermal energy is the sum of the kinetic and potential energies of all of the molecules.

13. Temperature vs. Thermal Energy
Which has higher temperature, an iceberg or a cup of tea?
Which has higher thermal energy, an iceberg or a cup of tea?

14. Temperature scales
Three temperature scales are in use today. Celsius (or Centigrade) is based on water. The freezing point of water is 0°C and the boiling point is 100°C. The Kelvin scale uses the same size for its degrees but shifts its zero to absolute zero (-273°C). On the Fahrenheit scale, the freezing point of water is 32°F and the boiling point is 212°F.

15. Thermal expansion
Most substances expand with heat. When they expand, they retain their proportions. The amount of expansion for a given change in temperature is a property of the substance - different substances expand different amounts. This explains why heating a jar lid will make it easier to open the jar. The metal lid expands more than the glass jar under the hot water.

16. Bimetallic strip
Bimetallic strips bend because one metal expands more than the other for a given change in temperature. They are often used in thermostats.

17. Thermal expansion of water
pearson

18. Thermal expansion of water
Which of these statements are true?
As temperature increases between 0°C and 4°C, volume is decreasing because molecules are speeding up
At 4°C, the effect of ice crystals collapsing is balanced by the molecules speeding up
Above 4°C, volume increases because ice crystals are collapsing.
All of the above
None of the above
pearson

19. Heat vs. temperature
In everyday language, heat and temperature mean roughly the same thing. In physics, these two commodities are quite different. Temperature is related to the average speed at which molecules move. It is an intensive property - it does not depend on the amount of substance present. If something is hot, it means the molecules are moving fast. Something cold has slowly moving molecules.

20. Heat
Heat is energy transferred because of temperature differences. It is neither intensive nor extensive - it is the quantity of energy in transit.

21. Heat exchange
When two materials are in contact, they exchange heat until they come into thermal equilibrium. The heat lost by one is gained by the other until they are the same temperature.

22. Specific heat
Specific heat capacity is defined as the amount of heat needed to raise the temperature of a substance by 1 degree Celsius. Different substances have different capacities for storing internal energy, so applying the same heat to two substances can result in them having different temperatures, even if they have the same mass.

23. Specific heat of water Specific heat table
Water has a very high specific heat - it takes a lot of heat to raise its temperature. This is especially important for life on Earth. Water must lose a lot of heat to lower its temperature. That means oceans are very hard to freeze.
Specific heat table