2. How is heat (thermal energy) transferred?
6.P.3.1
Energy can be transferred from one system to another (or from a system to its environment) in different ways
thermally, when a warmer object is in contact with a cooler one
mechanically, when two objects push or pull on each other over a distance
electrically, when an electrical source such as a battery or generator is connected in a complete circuit to an electrical device
by electromagnetic waves 2

3. A hot cup of cocoa is left on the kitchen counter
A hot cup of cocoa is left on the kitchen counter. A bowl of ice cream is left on the dining room table. Describe what happens to both, and explain in terms of “thermal energy” and the motion of atoms.

4. How is Heat Transferred?
Heat is transferred in three ways:
6.P.3.1
Heat flows through materials or across space from warm objects to cooler objects, until both objects are at equilibrium.
Heat travels through solids, primarily by conduction.
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Radiation is energy that travels across distances in the form of electromagnetic waves.
Over time, thermal energy tends to spread out through a material and from one material to another if they are in contact (conduction).
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection 4

5. Thermal Energy Transfer
6.P.3.1
Heat travels through solids, primarily by conduction.
Over time, thermal energy tends to spread out through a material and from one material to another if they are in contact (conduction).
CONDUCTION: heat transferred when two objects touch.
(works best in solids) 5

6. Thermal Energy Transfer: Conduction
Conduction works better in solids (such as land and metals), but not as well in liquids and gases (air and water do not conduct heat as well.)
6.P.3.1
Heat travels through solids, primarily by conduction.
Over time, thermal energy tends to spread out through a material and from one material to another if they are in contact (conduction). 6

7. Conduction Ex. #2 Conduction Ex. #3 Conduction Ex. #1
Examples of conduction where heat is transferred from particle to particle. How is the thermal energy being transferred in each picture?
Conduction Ex. #2
Conduction Ex. #3
Conduction Ex. #1
the heat is transferred from the frying pan to the cooking egg
the heat is transferred from the hot coffee to the spoon
the heat is transferred from the feet to the cold tile floor
6.P.3.1
Heat travels through solids, primarily by conduction.
Over time, thermal energy tends to spread out through a material and from one material to another if they are in contact (conduction). 7

8. Thermal Energy Transfer
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection)
CONVECTION: heat transferred by the circulation or movement of a liquid or gas. (fluids) 8

9. Thermal Energy Transfer: Convection
A fluid is a liquid or gas and has the ability to flow.
Solids, however, maintain their position
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 9

10. Thermal Energy Transfer: Convection
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 10

11. Thermal Energy Transfer: Convection
When you look at the road in the summertime on a hot day, you may notice that the air above the road looks “blurry” – this is convection taking place as the hot air directly over the road absorbs the heat from the road and rises.
Although the explanation can be quite complex, convection can help explain why mirages are seen in the desert.
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 11

12. Examples of convection where heat is transferred in fluids.
Convection Ex. #1
Convection Ex. #2
Convection Ex. #3
Convection occurring in water inside a pot that is on a stove
Convection occurring in a room with a radiator.
Convection occurring in the atmosphere.
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 12

13. Convection Currents
The upward movement of warm air and downward movement of cool air forms convection currents.
Heated fluid (liquid or gas) expands, becoming less dense. Because it is less dense, it rises. Cooler fluids rushes in to replace the air that lifted up. As the warm fluid rises and cool fluid falls, a circular pattern is created known as a convection current
Eventually the warmer air cools
and begins to fall again.
COLD
HOT
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 13

14. 6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 14

15. Thermal Energy Transfer
If conduction deals with solids and convection deals with liquids and gases, how does heat arrive to Earth from the Sun? There is very little matter in the 93 million miles between the Sun and the Earth.

16. Thermal Energy Transfer
Heat can travel in waves without a medium (a liquid, solid, or gas).
These waves are called electromagnetic waves.

17. Electromagnetic Wave Spectrum

18. Thermal Energy Transfer: Radiation
6.P.3.1
Radiation is energy that travels across distances in the form of electromagnetic waves.
The heat you feel from a fireplace, campfire or the sun travels directly to you as infrared radiation. This is part of the Electromagnetic Wave Spectrum. 18

19. Thermal Energy Transfer: Radiation
6.P.3.1
Radiation is energy that travels across distances in the form of electromagnetic waves.
You can’t see infrared radiation, but you can feel it as heat. 19

20. The Electromagnetic Wave Spectrum
The light we see with our eyes is really a very small portion of what is called the "Electromagnetic Spectrum." The Electromagnetic Spectrum includes all types of radiation - from the X-rays used at hospitals, to radio waves used for communication, and even the microwaves you cook food with.

21. Thermal Energy Transfer: Radiation
6.P.3.1
Radiation is energy that travels across distances in the form of electromagnetic waves.
All of the forms of electromagnetic energy in the spectrum can travel through the universe as waves – we call this radiation. 21

22. Thermal Energy Transfer: Radiation
RADIATION: heat transferred through matter or empty space (no direct contact) by electromagnetic waves.
6.P.3.1
Radiation is energy that travels across distances in the form of electromagnetic waves. 22

23. Energy in the Atmosphere
Heat transfer by radiation
Heat transfer
by convection
Heat transfer
by convection
Heat transfer by conduction
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection)
Heat energy is transferred by a number of ways. 23

24. 6.P.3.1
Thermal energy is transferred through a material by the collisions of atoms within the material
Heat flows through materials or across space from warm objects to cooler objects, until both objects are at equilibrium.
Heat travels through solids, primarily by conduction.
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Radiation is energy that travels across distances in the form of electromagnetic waves.
Over time, thermal energy tends to spread out through a material and from one material to another if they are in contact (conduction).
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection 24

25. Conduction Video Clips
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 25

26. Convection Video Clips
Convection Current Video clip
6.P.3.1
Heat is circulated in fluids, both liquids and gases, through the process of convection.
Thermal energy can also be transferred by means of currents in air, water, or other fluids (convection) 26

27. Radiation Video Clips Radiation Video clip

28. Shout it out!!

29. Conduction?? Convection?? Radiation??
a. heating a cup of water in a microwave oven
b. seeing a lightning bolt
convection
conduction
e. a burner coil getting hot on an electric stove
c. electricity moving as a current
convection
d. heat moving within fluids
radiation
f. sun rays reaching earth
convection
i. air travels this way
g. the heat you feel as you stand in front of a fireplace
radiation
h. the handle of a cold spoon heats up when dipped in a hot bowl of soup
conduction
radiation
m. transfer of heat through space
conduction
l. frying a pancake on a griddle
convection
j. water in a pot boils
radiation
k. heat you feel as you hold your hand above a hot stove
p. fast moving atomic particles colliding with slower moving particles
conduction
radiation
o. heat moving as a wave
conduction
n. transfer of heat through solids

30. Review Rap
Review of conduction, convection, and radiation rap video

31. Which materials assist or limit thermal energy transfer?
6.P.3.3
There are some things that we use daily that we want to conduct heat easily. Most of these items are made of materials that conduct heat readily: aluminum, steel, copper. We call these materials thermal conductors. Similarly, there are things that we do not want to conduct heat (pot handles, spatula, cooking utensils) and these items are generally made of materials that limit heat transfer. We call such materials thermal insulators. Expansion joint strips in bridges allow for the bridge to expand in hot weather and not break. These same joint strips allow for the bridge to contract in cold weather and not break.
Electrical energy also passes through conductors. An electrical conductor is a material through which an electrical current can flow easily. An electrical insulator is a material through which electrical current does not readily flow. Electrical conductors include most metals, while most nonmetallic solids (rubber, glass, porcelain, ceramic) are insulators. 31

32. What do you think causes pot holes in the road?
Think about our last unit on Matter and our discussions of expansion…

33. Potholes form because asphalt road surfaces eventually crack under the heat of the day and the constant stresses of traffic. These cracks allow snow and rainwater to seep into the underlying dirt and gravel. During cold nights, the water freezes and expands, pushing out some of the dirt and gravel, leaving a hole when the water eventually melts. This whole process repeats itself over and over.
Even in places where the air temperature rarely falls below freezing, excessive rainfall or flooding can eat away at the road.

34. THERMAL CONDUCTORS
Some materials are good conductors of thermal energy – they let heat pass through them easily.

35. THERMAL CONDUCTORS
METALS, such as aluminium, copper, and steel are good THERMAL CONDUCTORS
...because heat passes through them quickly – metal normally feels COLD 35

36. THERMAL CONDUCTORS
Conductor – a material that transfers thermal or electrical energy very well.
* Conductors allow energy (thermal and electrical) to easily flow through them

37. Some Materials Do Not let Heat pass through them
THERMAL INSULATORS
Some Materials Do Not let Heat pass through them
Oven Mitt
Wooden handle
Wooden
handle

38. THERMAL INSULATORS
Wood, plastic, glass, wool and rubber are all insulators *insulators are poor conductors of both thermal and electrical energy
Wooden handle

39. THERMAL INSULATORS
Insulator – a material that does not transfer thermal or electrical energy very well.
Wooden handle

41. Insulators and Conductors both have important Uses
Wires are coated in plastic – electricity cant flow through it so you don’t get a shock if you touch it
Copper wire allows electricity to flow through

42. Insulators and Conductors both have important Uses
A plug has metal pins – conduct electricity,
and a plastic cover to hold with your hands

43. Thermal Expansion: an increase in the size of a substance in response to an increase in the temperature of the substance.
background 43

44. Can energy transform (change)?
6.P.3.3 44

45. Energy Transforming
The law of conservation of energy states that energy can neither be created nor destroyed. It can only be converted from one form to another.
background 45

46. Energy Transforming

47. Energy Transforming
Some thermal energy in all materials is transformed into light energy
6.P.3.3 47

48. Energy Transforming
For example, a light bulb works by transforming electric energy into thermal energy. The thermal energy is then transformed into light energy.
ELECTRIC
ENERGY
THERMAL
ENERGY
LIGHT
ENERGY

49. Energy Transforming
Light energy is radiated into the environment by electromagnetic waves.
6.P.3.3 49

50. Energy Transforming
Once the electromagnetic waves strike another material they are transformed back into thermal energy.
if you put your hand near a lit light bulb, you can FEEL the heat, without touching it