1. Unit 3 Nature’s Energy 1

2. 1. Heat Energy

3. Energy passed as heat from one object to another
Heat always passes from a hotter object to a cooler object

4. If you hold an ice cube in your hand,
it will start to melt

5. Heat energy passes from your hand to the ice cube
The heat energy makes the molecules in the ice move faster

6. The ice begins to melt,
or become a liquid

7. Heat energy can be passed in 3 ways
Conduction
Convection
Radiation

8. When heat passes through solids
Vocabulary
conduction
When heat passes through solids 8

9. When one object passes heat to another by conduction,
The heat keeps flowing until both objects are equally hot 9

10. Have you ever eaten hot soup with a metal spoon?
After a while, the spoon gets hot 10

11. The hot soup causes the molecules in the spoon to move faster
Heat travels from the soup up the spoon to your hand 11

12. When heat passes through liquids and gasses in currents
Vocabulary
convection
When heat passes through liquids and gasses in currents 12

13. Molecules in liquids and gases move apart when they are heated
This happens during convection 13

14. When you heat water on the stove,
The bottom layer of water is heated first
The molecules in this layer of water move farther apart 14

15. Then floats to the top, and the cooler, heavier water on the top falls to the bottom15

16. These molecules are called convection currents
In winter, convection heats the air in your house 16

17. Vocabulary
Convection currents
movement of warm molecules rising as they push the cooler molecules downward

18. Solar heat comes in radiation waves18

19. Movement of energy in waves
Vocabulary
radiation
Movement of energy in waves

20. Microwave ovens heat food by
radiation 20

21. Heat energy can be passed in 3 ways
Conduction - contact
Convection - current
Radiation - waves 21