Physics for You

1
Plenary
AQA P1a.1
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Chapter 9 AQA topic P1a.1 Thermal Energy (heat)
Transfer
2
Thermal Energy (heat) Transfer
AQA P1a.1

• Metals are good / poor conductors of heat because
  they have many / few ???? electrons in their
  structure.
• The tiles on my bathroom floor feel cold under
  my feet, but the rug feels warm. Yet theyre
  both at the same temperature! Why do they feel
  different?
• Name 3 ways to reduce heat loss from a house.

3
Thermal Energy (heat) Transfer
AQA P1a.1
Answers

• Metals are good / poor conductors of heat because
  they have many / few ???? electrons in their
  structure.
• The tiles on my bathroom floor feel cold under
  my feet, but the rug feels warm. Yet theyre
  both at the same temperature! Why do they feel
  different?
• Name 3 ways to reduce heat loss from a house.

good
free
many
Its not a temperature question its a
conduction question. The rug is a poor
conductor, so it doesnt take much heat away from
my feet.
(any 3 sensible answers)
4
Thermal Energy (heat) Transfer
AQA P1a.1

• Explain why a hot air balloon can fly. (3
  marks)
• Explain why two thin blankets keep youwarmer
  than one thick blanket . (3 marks)

5
Thermal Energy (heat) Transfer
AQA P1a.1
Answers

• Explain why a hot air balloon can fly. (3
  marks)
• Explain why two thin blankets keep youwarmer
  than one thick blanket . (3 marks)

Air is heated by the burner and expands(1), so
it is less dense(1) than the surrounding air, so
it tends to rise(1). 3 marks Simply because
hot air rises 1 mark Heat rises WRONG! No
marks
Air is a poor conductor, so it is a good
insulator(1) but only if it is trapped, to stop
convection currents(1). Two thin blankets will
trap more air(1). 3 marks
6
Thermal Energy (heat) Transfer
AQA P1a.1

• Black / shiny surfaces absorb heat well.
• Black / shiny surfaces emit heat well.
• Conduction / convection / radiation is the main
  method of heat transfer in solids.
• In a vacuum flask,- why has the air been sucked
  out from between the glass walls?- what is
  the shiny layer for?

7
Thermal Energy (heat) Transfer
AQA P1a.1
Answers

• Black / shiny surfaces absorb heat well.
• Black / shiny surfaces emit heat well.
• Conduction / convection / radiation is the main
  method of heat transfer in solids.
• In a vacuum flask,- why has the air been sucked
  out from between the glass walls?- what is
  the shiny layer for?

To stop conduction and convection.
To reflect thermal radiation (infra-red).
8
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