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Heat Transfer
• Heat transfer
• Everything is made of molecules. • When molecules gain energy they
move faster and create more heat.
• (The faster the molecules move the hotter they are)
Melting Evaporation
CondensationFreezing
liquidSolid Gas
Molecules move very slowly! They are close together.
Molecules move faster and are more spread apart.
Molecules move very fast! They are very spread apart.
• Heat • Is the transfer of thermal energy from a hotter object to a cooler one until both objects are the same temperature.
(You can not transfer cold or give someone cold)
heat transfer video clip
On a hot sunny day, have you ever seen cars, buildings, or other objects appear to shimmer or waver on the other side of a
street or parking lot?
• Explanation: Sun is heating up the ground more quickly than it heats the air, especially if the surface of the ground is a dark color. The heated air rises and bends light waves as it passes through them. Making the objects on the other side shimmer.
3 ways that heat is transferred within the
atmosphere
•Radiation•Conduction •Convection
The first method of heat transfer
How does heat energy get from the Sun to the Earth?
?RADIATION
• Radiation
What createselectromagnetic
waves?
Video clip 1video clip 2Eureka start at 2:30
• The direct transfer of energy by infrared electromagnetic Waves.
• Sun, fire, light bulbs
Pair Share
• Partner A: What is radiation and where does it come from.
• Partner B: What are three different things that create electromagnetic radiation?
•Conduction
•conduction video clip 1
•Eureka
• The direct transfer of heat from one substance to another substance that is touching.
That’s Hot
Ironing Clothes
Stepping on hot sand.
Objects have to touch!!!
ConductionWhen you heat a metal strip at one end, the heat travels to the other end.
As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this?
Conduction Example
• Stir your hot soup with a metal spoon• Pretty soon you need a pot holder
because the end of the spoon you are holding gets hot
• This is heat transfer by conduction• Energy travels up the spoon from the
end in the hot soup to the end in your hand
Example of Conduction
Pair Share: Partner A: Using the
picture on the right explain the conduction process
Pair Share: Partner B: Explain how the
picture on the left is conducting heat.
• Convection
• convection video clip
• Convection 2
• Convection- Eureka
• The transfer of heat by movement of a fluid (liquids and gases).
OVEN
Dryer
Cooking peas in water
Blow Drying your Hair.
Convection
What happens to the particles in a liquid or a gas when you heat them?
The particles spread out and become less dense.
This effects fluid movement.What is a fluid?A liquid or gas.
Water movement
Hot water rises
Cooler water sinks
Convection current
Cools at the surface
Freezer compartment
It is put at the top, because cool air sinks, so it cools the food on the
way down.
It is warmer at the bottom, so this warmer air
rises and a convection
current is set up.
Why do most refrigerators have the freezer on top. Hint think about the principle of convection.
Conduction, Convection and Radiation
• Heating the troposphere
• Radiation, conduction and convection work together to heat the troposphere.
• Radiation- heats the Earth • Conduction- Air near earth’s
surface is warmed• Convection- the warm air
molecules rise and transfer heat to the cooler air molecules. Eventually these molecules cool and sink back down to earth. This creates Convection Currents.
Radiation
Radiation, Convection and Conduction work together to heat the troposphere.
review of all 3 types
Conduction
Convection Current
Radiation, Convection and Conduction work together to heat the troposphere.
ReviewHeat transfer from a hotter object to a cooler
object until both objects are the same temperature.
3 types of heat transfer review, review 2Music Review• Radiation – electromagnetic waves• Conduction – touching• Convection- through a fluid (liquid or gas)• All 3 work together to heat the troposphere
but Convection causes most of the heating.