1. Thermodynamics: the study of thermal energy

2. Heat is NOT temperature. You do NOT measure heat with a thermometer! Heat is the flow of energy. Heat: Transfer of “disordered” energy at the microscopic level as a result of temperature differences Unit: Joules (just like all forms of energy) James Joule first determined the relationship between mechanical energy and heat- (motion transformed into heat)

3. An older unit for measuring heat was the “calorie”. One food Calorie = 4186 Joules I wonder how many joules of energy are in this strawberry shortcake?

4. What is “Cold”? Just as darkness is an absence of light, Cold is a absence of heat. Heat flow is a measurable quantity. As more and more heat flows out of something, it gets colder and colder.

5. When two substances of different temperatures are in contact, heat will flow until they are at the same temperature, “thermal equilibrium”

6. Transfer of Thermal Energy Convection- the bulk flow of fluids, (gases or liquids, NOT solids) “convection currents” Conduction- direct contact Radiation- electromagnetic waves

8. Conductivity A block of wood and a block of metal sit on a table. You touch each. Which one feels colder? Is it really colder? Why does it feel that way?

9. Thermal Conductivity: The ability to conduct heat. Thermal Insulators do not conduct heat readily. Generally, metals have high thermal conductivity and gases have low thermal conductivity.

10. For metals, the thermal conductivity is quite high, and those metals which are the best electrical conductors are also the best thermal conductors.metals electrical conductors Best conductors Both heat & electrical In order: Silver Copper Gold Aluminum

11. Temperature scales CelsiusC = 5/9(F° – 32) FahrenheitF = 9/5C° + 32 KelvinK = C° + 273

12. Water (at normal Earth atmospheric pressure) freezes at 0°C = 32°F boils at 100°C = 212°F

13. Is there a HOTTEST possible temperature? Temperatures do not appear to have an upper limit. Is there a COLDEST possible temperature? The lower limit on temperature is called “absolute zero”, which equals 0 Kelvins. However, it is impossible for a substance to be at absolute zero.

14. The Kelvin scale, which has its zero at ABSOLUTE ZERO, was named for William Thomson, “Lord Kelvin”, who found the value for absolute zero using fundamental laws of thermodynamics.

15. What is “Absolute Zero”? For ALL gases, as the temperature drops, the pressure within the gas drops in a direct relationship. Graphing pressure vs temperature for many gases and then EXTRAPOLATING the graphs to a pressure of ZERO (which is impossible) yields the same temperature for every gas: -273 C = 0 Kelvins = Absolute Zero