Unit 1

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Heating Houses (P1)

Enery flows from a warmer to a colder body.

A thermogram uses colour to show temperature. Hot: white/yellow and cold: black/dark blue/purple.

Temperature is a measure of hotness = arbitrary scale. Temp increases, average KE of particles increases.

Heat is a measurement of internal energy: absolute scale

Specific heat capacity

- energy needed to raise the temp of 1 kg by 1C

- measured in joules per kg (J/Kg C)

Specific latent heat

- energy needed to melt or boil 1 kg of material (J/Kg)

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Practical Insulation (P1)

Double glazing: reduces energy loss by conduction

- Makes it difficult to transfer energy in the gap and there are no particles in a vacuum

Loft insulation: reduces energy loss by conduction and convection

with: warm air rises, energy is transferred through ceiling by conduction and is trapped by loft insulation (both sides of ceiling are the same temp = no energy transferred)

without: warm air can move by convection and energy is transferred to outside by conduction.

Cavity wall inslation: reduces energy loss by conduction and convection

- Air in foam is a good insulator and cannot move by convection = foam traps it.

Insulation blocks (shiny foil on both sides)

- energy from sun is relected back = house cool in summer

- energy from home is reflected back = warm in winter

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