Thermal Energy Transfer

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Thermal Energy Transfer

• Convection, Conduction, Radiation

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Getting Energy

• All energy on Earth comes from the Sun, but
  there are three different ways things can get the
  energy once it is here.

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Three Forms of Thermal (Heat) Transfer

• Radiation - transferred through space (does not
  need a material medium)
• Conduction - the transfer of heat through direct
  contact or touch
• Convection transfer of heat as molecules move
  in currents
• THERMAL ENERGY always moves in the direction of ?
  from the warmer area to the colder area.

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Radiation heat is transferred through space
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Radiation SOLAR - Energy travels from the sun in
electromagnetic waves. These waves are absorbed
by the things on earth.
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The solar radiation heats the surface of the
earth.
Conduction - Heat is transferred to air molecules
that come in direct contact with the ground.
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• The air touching the ground is warmed through
  conduction.

Conduction is when heat is transferred by direct
contact or touch.
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Conduction - the transfer of heat through direct
contact in a metal rod
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• When a lizard basks on a rock in the desert to
  warm its body, the thermal energy in the rock is
  transferred to the lizard through conduction or
  direct contact!

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2. Air is warmed by conduction
1. Ground warmed by radiation
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Energy causes weather experienced on Earth...

• As the air heat up
• it rises
• into the atmosphere

2. Then it falls back to the Earth as it cools.
3. Cooler air is pulled in from other places
Do you know what this is called?
CONVECTION!!!
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• The atmosphere is warmed through convection.

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4. Convection Rising air spreads heat throughout
the atmosphere in currents.
3. As the air becomes less dense it rises
2. Air is warmed by conduction
1. Ground warmed by radiation
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Convection transfer of heat as molecules move
in currents
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Convection
Warmer Air

• The transfer of heat by the movement of warm
  matter.
• EX Heat leaves the coffee cup as the currents of
  steam and air rise.
• Consider This convection is responsible for
  making macaroni rise and fall in a pot of heated
  water. The warmer portions of the water are less
  dense and therefore, they rise. Meanwhile, the
  cooler portions of the water fall because they
  are denser.

Cooler Air
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Questions
CONVECTION IN LIQUID

• Which way does the warmed water move ?
• What happens when it reaches the surface?
• Which way does the cooler water on the edges
  move?
• Is warmer water denser or less dense than cooler
  water? Are the water molecules moving faster or
  slower in warmer water?

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Explanation
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Heat can transfer in 3 ways
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Critical Questions

• What are the three types of heat transfer?
• How is conduction different from convection?
• What type of heat transfer is involved in
• Heating a room with a fireplace
• Egg cooking in a frying pan
• Roof of a house becoming hot

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Videosclick to open the link, then view video
in full screen mode.Bill Nye Heat Part
onehttp//www.gamequarium.org/cgi-bin/search/linf
o.cgi?id7913Bill Nye Heat Part
threehttp//www.gamequarium.org/cgi-bin/search/li
nfo.cgi?id7915Bill Nye Heat Part two
http//www.gamequarium.org/cgi-bin/search/linfo.c
gi?id7914