1. Ch. 13 - Energy II. Thermal Energy  Temperature  Thermal Energy  Heat Transfer

2. A. Temperature Temperature  A measure of the average kinetic energy of an object’s atoms or molecules  A measure of how hot (or cold) something is.

3. Temperature & KE The higher the temperature the more kinetic energy the particles in the substance have. The lower the temperature the less kinetic energy the particles in the substance will have.

4. B. Thermal Energy Thermal Energy  the sum of the kinetic and potential energy of all the atoms in an object  Thermal energy increases as temperature increases  At constant temperature, thermal energy increases if mass increases.

5. B. Thermal Energy Which beaker of water has more thermal energy?  B - same temperature, more mass 200 mL 80ºC A 400 mL 80ºC B

6. C. Heat Transfer Heat- the energy transfer between objects that are at different temperatures. Energy is always transferred from higher temperature objects to cooler temperature objects.

7. C. Heat Transfer Why does A feel hot and B feel cold? 80ºC A 10ºC B  Heat flows from A to your hand = hot.  Heat flows from your hand to B = cold.

8. Heat Transfer Transformations of energy usually produce heat! In all Energy transfers, the energy is spread out uniformly. There are 3 types of energy transfers: 1. Conduction 2. Convection 3. Radiation

9. Heat Transfer 1. Conduction  The movement of heat through material.  The heat energy is passed from molecule to molecule  Conduction requires direct contact in order for heat to transfer.

10. Conduction Example: When you grab the handle of a hot pan on the stove, conduction transfers some of the heat in the pan to your hand resulting in a pain or burn.

11. Heat Transfer 2. Convection  The transfer of thermal energy by the fluid (gas or liquid) of heated matter particles Convection currents transfer heat from warmer to cooler parts of a fluid

12. Convection Example: A convection oven utilizes a fan to better move the heated air around the food so that it cooks faster.

13. Heat Transfer 3. Radiation  energy transfer by electromagnetic waves  Electromagnetic waves do NOT require a medium in order to travel, therefore, solar radiation can travel through outer space to warm the earth!

14. Radiant energy can be absorbed, reflected, or transmitted depending upon the properties of the material receiving the energy. Some forms of radiation (radiant energy) can pass through solids, liquids and gases. All objects give off radiant energy! Yes, even us!

15. D. Conductors and Insulators Conductor – any material through which energy can be easily transferred as heat  Examples – metals (copper) Insulator – any material through which energy cannot be easily transferred as heat – a poor conductor

16. Let’s review… https://www.youtube.co m/watch?feature=play er_detailpage&v=7Y3 mfAGVn1c