heat transfer
DESCRIPTION
GCSE Physics double award notesTRANSCRIPT
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Heat Energy Transfer
GCSE Physics
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Textbook reference
• CCEA Physics, Page 17 – 25
• Key words list, what do you think the words and phrases mean?
• You don’t want to get confused… like President Bush!
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Learning Intentions
• State the three types of heat energy transfer
• Recall in detail how the three types of heat energy transfer occur.
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Don’t let the cold in!!!
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Heat Transfer
• Heat Flow• Objects get hot if heat energy (thermal
energy) passes into them. We know they get hot because the temperature rises. It is important that we know the difference between temperature and heat:
• Temperature - the measure of how hot something is, measured in degrees Celsius;
• Heat - a flow of energy from a hot object to a cold object. Heat is measured in joules (J).
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Particle motion in a substance
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Heat Flow
• Heat always flows from hot to cold. Heat does not flow from a cold object to a hot object. For example the heat from a hotplate passes into a cold pan to heat up the water in the pan.
• The greater the temperature difference between the hot object and the cold object, the greater is the flow of heat.
HOT HEAT COLD
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Types of Heat Energy Transfer
• Page 17- The three ways in which heat can
move (types of heat energy transfer) are…
• ConductionConduction• ConvectionConvection• RadiationRadiation
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Convection
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Which weighs more?
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Convection
• Structure of a Liquid and a Gas
Both states of matter flow and carry the heat energy with them.
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Particles move feely
Gain heat energy
Move faster and spread out
Volume becomes
less dense
Rises and
bringing the heat
energy
What causes the convection currents?
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The movement of hotter areas in a liquid can be seen using potassium permanganate as a dye:
H E A T
This cycle is called a convection current.
Can you explain how the convection current moves using the idea of density?
The diagrams on the left will help you.
Change in Density
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Question Time
• CCEA Physics • Attempt Q 33 pg 24 and Q 5a pg 30
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Conduction
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Conduction
• Structure of a Solid (cannot flow)
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Conduction in Solids
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1919
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Radiation
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Application of Heat transfer
• Trapping layers of air in between bed sheets• Skin cancer• Cooking utensils• A greenhouse• Table mats, handles of cooking appliances • Air con is usually placed at the top of a room• A heating coil of a kettle is at the bottom• Formation of land and sea breezes• Silver Teapots and pans• Different hot and cold touch sensations from
objects• Colour and texture of clothing
Conduction, Convection or Radiation??
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Newspaper Headlines!
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Greenhouse Gases…
• Water Vapour
• Carbon Dioxide
• Methane
• Halocarbons
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Questions
• Text Book pg 29• Questions 4 – 7
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The internet can help!
• http://www.bbc.co.uk/climate/evidence/
• Evidence• Impacts• Adaptation
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Reducing the runaway greenhouse effect
• http://www.bbc.co.uk/climate/adaptation/jack.shtml
• Life at Home• Copy down what we can do to help
slow this down!