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2.3 Understanding thermal energy

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Heat transfer, convection, conduction, radiation

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2.3 Understanding thermal energy

  1. 1. 10 October 2010<br />2.3 Understanding thermal energy<br />Order these objects in the lab from coldest to warmest. Go touch them to help you decide.<br />Wooden desk<br />Metal tap<br />Plastic whiteboard<br />Tiled floor<br />Concrete wall<br />
  2. 2. Metal container<br />Which ice cube melts quicker?<br />Cardboard<br />
  3. 3. Conduction<br />
  4. 4.
  5. 5. Conduction<br />Atoms vibrate, the higher the temperature the greater the temperature.<br />Metals are the best conductors as they have lots of free electrons.<br />
  6. 6. Activity A<br />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.<br />
  7. 7. Convection<br />
  8. 8.
  9. 9. Convection<br />The atoms in fluids are free to move. When they do so they transfer heat – this is called convection<br />
  10. 10. Activity B<br />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.<br />
  11. 11. Radiation<br />
  12. 12.
  13. 13. Radiation<br />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.<br />
  14. 14. Assessment activity 2.3<br />Explain why the whole pan of soup gets hot, even if you don’t stir it. P1<br />Work in groups of 2 or 3. Produce a leaflet showing different ways we use heat transfer in the home and the work place<br />REMEMBER: solids transfer heat energy by conduction and fluids by convection. Radiation is light and doesn’t need a medium to transfer through<br />

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