1. Temperature and Thermal Energy Thermodynamics 2011-2012

2. Temperature A measure of the average kinetic energy of the particles in a substance. Adding or removing energy usually changes temperature. It is proportional to the kinetic energy of atoms and molecules.

3. Measuring Temperature Three Temperature Scales: Celsius Kelvin Fahrenheit

4. Heat The energy transferred between objects because of a difference in their temperatures. Energy is transferred as heat from objects with higher temperatures to those with lower temperatures. Heat has units of Joules (J)

5. Heat, continued Total energy is conserved. change in potential + change in kinetic + change in internal energy = 0

6. Thermal Equilibrium Temperature is only meaningful when stable. Thermal equilibrium – the state in which two bodies in physical contact with each other have identical temperatures Matter expands as its temperature increases.

7. Conduction The transfer of energy as heat through a material between two points at different temperatures. Example: Heating a metal rod  The flame will increase the kinetic energy of the atoms closest to it, which in turn will bump into other free atoms, causing their kinetic energy to increase, and so on. A good insulator is a poor conductor.

8. Convection The displacement of cold matter by hot matter. Heating occurs by currents. Example: Lava Lamp  The wax warms from the lamp, rises to the top, cools, then falls back to the bottom and the cycle repeats

9. Radiation Here, we are not speaking of radioactivity. Energy in the form of electromagnetic waves. Examples: Microwaves, IR radiation, visible light, UV radiation, X- rays, gamma rays

10. Specific Heat The quantity of energy needed to raise the temperature of 1 kg of a substance by 1° C at constant pressure. Relates mass, temperature change and energy transferred.

11. Specific Heat, continued Q – energy transferred as heat m – mass ΔT – temperature c – specific heat capacity

12. Specific Heat, continued Applies to substances that absorb energy from their surroundings and those that transfer energy to their surroundings. When temperature increases, ΔT and Q are positive  energy transferred into the substance When temperature decreases, ΔT and Q are negative  energy transferred out of the substance

13. Specific Heat, continued SubstanceSpecific Heat Capacity – c (J/kg°C) Aluminum897 Copper385 Glass840 Gold129 Ice2060 Iron450 Lead130 Mercury138 Silver235 Steam2020 Water4180

14. Change in Thermal Energy