2.3 understanding thermal energy
DESCRIPTION
Heat transfer, convection, conduction, radiationTRANSCRIPT
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2.3 Understanding thermal energyApril 12, 2023
Order these objects in the lab from coldest to warmest. Go touch them to help you decide.
Wooden deskMetal tapPlastic whiteboardTiled floorConcrete wall
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Metal container
CardboardWhi
ch ic
e cu
be m
elts
qui
cker
?
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Conduction
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Conduction
• Atoms vibrate, the higher the temperature the greater the temperature.
• Metals are the best conductors as they have lots of free electrons.
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Activity A
• Imagine heating up some baked beans in a metal saucepan. You stir the beans with a metal spoon. Using the idea of conduction, explain why the spoon gets hot.
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Convection
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Convection
• The atoms in fluids are free to move. When they do so they transfer heat – this is called convection
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Activity B
• Now imagine heating up some soup. Even if you don’t stir it, the whole pan of soup eventually heats up. Use the principle of convection to explain why.
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Radiation
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Radiation
• Heat is transferred through infra-red radiation. It doesn’t involve anything. It is mostly absorbed by dark, dull objects and reflected by bright, shiny objects.
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Assessment activity 2.3
1. Explain why the whole pan of soup gets hot, even if you don’t stir it. P1
2. Work in groups of 2 or 3. Produce a leaflet showing different ways we use heat transfer in the home and the work place
REMEMBER: solids transfer heat energy by conduction and fluids by convection. Radiation is
light and doesn’t need a medium to transfer through