1. Chapter 22: Heat Transfer

2. Which “way” does heat flow? Heat flows from high temperature to low temperature

3. T/F The metal part of your desk feels cooler than the top because it’s at a lower temperature. False. Metals are good conductors of heat energy.

4. Conduction Occurs within the material and/or between the material and what’s touching it. Metals are the best conductors: Silver, Cu, Al, Fe Loose outer electrons in good conductors Atoms vibrate and bump into one another and free electrons drift through the metal and collide with atoms and other free /loose electrons

5. Why are metals good conductors of heat? They have the loosest outer electrons.

6. What is the opposite of a conductor? An insulator!

7. Insulators Insulators have tightly-bound electrons that delay the flow of heat. Air, wood, plastic, glass, ceramic, rubber Styrofoam, fiberglass insulation, snow all have a lot of space to trap air.

8. You can stick your hand inside a hot oven for several seconds without harm, whereas you’d never touch the metal inside surfaces for even a second. Why? Air is a poor conductor of heat and metal is a very good conductor of heat.

9. Convection Occurs in fluids (liquids and gases) Molecules move from one place to another-convection currents

10. Convection Heaters and Ovens

11. How are winds produced? Ocean breezes?

12. Absorption of Radiant Energy Absorption and reflection are opposites Black is a good absorber Pupil of the eye is black to absorb light Good reflectors are poor absorbers

13. Emission of Radiant Energy A good absorber is a good emitter Black is a good absorber and a good emitter of radiant energy

14. Would your hot beverage stay warmer longer in a black or white mug? Why? White mug because black is a good emitter of radiant energy.

15. Why are Thermos bottles silver on the inside?

17. Newton’s Law of Cooling The rate of cooling (how fast it happens) depends on the difference in temperature between the object ant its surroundings. Where would the pie cool faster? Why?

18. Global Warming and the Greenhouse Effect

19. The Greenhouse Effect Short waves from the sun pass through atmosphere They’re absorbed by the earth and objects and change to long waves (heat) Some of the long waves (heat) can’t escape into space and are trapped in the atmosphere