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Do now!

He’s going to blow!. Be careful. Neutral. Good. Excellent. MOODOMETER. Can you finish the sheet you started on Friday (“Testing insulation 1”)?. Do now!. A reminder. Heat can travel by Conduction. Hot particles vibrate more, so collide with adjacent particles.

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Do now!

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  1. He’s going to blow! Be careful Neutral Good Excellent MOODOMETER Can you finish the sheet you started on Friday (“Testing insulation 1”)? Do now!

  2. A reminder

  3. Heat can travel by Conduction • Hot particles vibrate more, so collide with adjacent particles. • Metals are good conductors because the atoms are close together and free electrons can carry energy too. • Gases are poor conductors because the particles are farapart.

  4. Heat can travel by Convection A hot fluid expands, is less dense, so rises. Cold fluid takes its place. A convection current can be formed.

  5. Infrared radiation • Heat can travel by infrared radiation (“Hot light”!)

  6. Infrared radiation Black objects are good absorbers of infrared radiation.

  7. Infrared radiation Shiny objects reflect infrared radiation. Nottingham Forest winning the champions league in 1979

  8. Insulation! Today’s lesson

  9. Insulation Investigation Stick the sheet in and read it.

  10. Vacuum Flask (“Thermos”)

  11. The insulated lid stops the heat escaping (and entering) by convection

  12. The vacuum between the two walls stops the heat escaping (and entering) by conduction vacuum

  13. The silvered inner and outer stops the heat escaping (and entering) by radiation silvered outer silvered inner

  14. This means hot liquids stay hot because the heat cannot escape Hot chocolate

  15. This means cold liquids stay cold because the heat cannot enter Cold Vimto

  16. In reality, some heat escapes via the lid and eventually the liquid inside will become the same temperature as the surroundings

  17. In a perfect flask without a lid, a hot drink would stay hot forever! Hot chocolate

  18. The vacuum flask Can you complete the sheet please?

  19. Questions! Can you do the questions on pages 106 and 107?

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