1. C HAPTER 2; S ECTION 2 Heat transfer

2. T HINK ABOUT IT … If you add ice to lemonade on a hot summer’s day why does the ice melt? Choose the best answer: A. The coldness from the ice moved into the lemonade B. The heat from the lemonade moved into the ice C. The coldness and heat moved back and forth until the lemonade cooled off

3. The correct answer is B. The heat from the lemonade moved into the ice. Heat energy is transferred from one place to another through the process of heat flow. This thermal energy will only move from a warmer object to a cooler object, never the other way around. Heat went into the ice from the lemonade, cooling the lemonade and melting the ice

4. H EAT CAN BE TRANSFERRED IN 3 WAYS :

5. R ADIATION The flow of energy through space and matter. Examples include visible light, radio waves, and radiant heat. Can be in the form of particles or waves.

6. E XAMPLES OF RADIATION ( HEAT )

7. C ONVECTION The transfer of heat by a liquid or gas (such as air). Can only occur in liquids and gases (relatively big spaces between the molecules) A convection current is where hot air rises and cold air sinks.

8. W HY DOES HEAT RISE ? Molecules that are heated move around faster, causing them to spread apart (the AIR expands, not the molecules) This causes the air to be less dense (and less heavy), so it rises When air rises, it will cool off and become more dense (the air condenses), so it will fall down again.

9. E XAMPLES OF CONVECTION

10. C ONDUCTION The direct transfer of heat from one substance to another substance that is touching it. Molecules can pass heat energy to adjacent molecules, heating them as well Conduction works better it certain substances, like metals

11. E XAMPLES OF CONDUCTION

12. A LL 3 TYPES WORK TOGETHER :

13. H EATING IN THE TROPOSPHERE How does each type of heat transfer heat the Earth? See page 51 in book