1. Chapter 10 H e a t

2. Heat & Temperature Temperature is _____. –how hot or cold something is (a physical property) –related to the average (kinetic) energy of the substance (not the total energy) –Measured in units of Degrees Fahrenheit ( o F) Degrees Celsius ( o C) Kelvin (K)

3. Temperature Scales Fahrenheit Scale, °F –Water’s freezing point = 32°F, boiling point = 212°F Celsius Scale, °C –Temperature unit larger than the Fahrenheit –Water’s freezing point = 0°C, boiling point = 100°C Kelvin Scale, K –Temperature unit same size as Celsius –Water’s freezing point = 273 K, boiling point = 373 K

4. A b s o l u t e Z e r o T h e t e m p e r a t u r e a t w h i c h a l l m o l e c u l a r m o t i o n s t o p s. T h e t e m p e r a t u r e w o u l d b e z e r o K e l v i n s o r a b o u t - 2 7 3 o C. T h e t e m p e r a t u r e a t w h i c h a l l m o l e c u l a r m o t i o n s t o p s. T h e t e m p e r a t u r e w o u l d b e z e r o K e l v i n s o r a b o u t - 2 7 3 o C.

5. Temperature of ice water and boiling water.

6. Heat Heat is the flow of energy due to a temperature difference –Heat flows from higher temperature to lower temperature Heat is transferred due to “collisions” between atoms/molecules of different kinetic energy When produced by friction, heat is mechanical energy that is irretrievably removed from a system

7. H e a t T r a n s f e r H e a t T r a n s f e r H e a t T r a n s f e r – C o n d u c t i o n – C o n v e c t i o n – R a d i a t i o n H e a t T r a n s f e r H e a t T r a n s f e r – C o n d u c t i o n – C o n v e c t i o n – R a d i a t i o n

8. Conduction Through a Heated Rod HOT (lots of vibration) COLD (not much vibration) Heat travels along the rod

9. Convection Convection is heat transfer by bulk movement within a heated fluid such as a liquid or a gas. Free convection is caused by expansion of fluids when heated, causing hot regions to become buoyant. Circulation occurs as the hot fluid cools and sinks down again. Free convection systems can be very large and convey massive amounts of heat, for instance in weather systems and the circulation of molten rock inside the Earth. Radiators make use of convection to transfer the heat from hot materials (water, night storage bricks) to a room.

10. Specific Heat Why do some foods stay hot longer than others? Why is the beach sand hot, but the water is cool on the same hot day?

11. Heat (cont.) The heat energy absorbed by an object is proportional to: –The mass of the object (m) –The change in temperature the object undergoes (  T) –Specific heat capacity (s) (a physical property unique to the substance) To calculate heat (Q): Q = c. m.  T

13. Specific Heat Different substances have different capacities for storing energy It may take 20 minutes to heat water to 75°C. However, the same mass of aluminum might require 5 minutes and the same amount of copper may take only 2 minutes to reach the same temperature.

14. Specific Heat Different substances have different capacities for storing energy It may take 20 minutes to heat water to 75°C. However, the same mass of aluminum might require 5 minutes and the same amount of copper may take only 2 minutes to reach the same temperature.

15. Plates?

16. Plate

19. Review of Plate Tectonics What drives Earth processes? –gravity and density differences –external (e.g. hydrologic cycle, erosion) –internal (e.g. mantle convection)

20. Plate Boundaries divergent (constructive) transform convergent (destructive) –ocean-ocean (e.g. Mariana Islands) –ocean-continent (e.g. Pacific-North America) –continent-continent (e.g. India-Asia)