Materials and their

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Materials and their Properties
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Comparing Materials

• Materials have certain PROPERTIES which make them
  USEFUL
• We need to be able to describe and compare the
  properties of a material and say why its used for
  a job. We use certain materials for certain jobs

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strong

• Steel Bridge

Plastic container
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hard
Metal hammer head
Diamond ring
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flexible
Leather belt
Fishing rod
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Rigid
Metal scaffolding
ladder
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transparent
window
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absorbent
Paper towels/tissues
towelling
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stretchy
Stretch fabric
Elastic band
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squashy
springs
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Conductors and Insulators of Heat

• Some Materials let Heat pass through them Easily
• These materials are called THERMAL CONDUCTORS
• METALS are good THERMAL CONDUCTORS
• Because heat passes through them quickly metal
  normally feels COLD

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Some Materials Do Not let Heat pass through them

• 1) Materials that do not let heat pass through
  them are called THERMAL INSULATORS.

Oven glove
Wooden handle
thermals
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• 2) Plastic, cork, wood and fabrics are good
  THERMAL INSULATORS
• 3) Thermal insulators are good for keeping heat
  OUT as well as IN

Fridge keeps heat out
Polystyrene cup keeps heat in
Thermos Does both
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A good insulator a poor conductor
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Heat travels from a warmer material to a colder
one
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Conductors and Insulators of Electricity

• Conductors let electricity flow through them
• 1)Materials that can carry electricity are called
  conductors they conduct electricity
• 2) Metals like copper, iron, steel and aluminium
  are all good conductors.

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Insulators do not let electricity flow through
them

1. Materials that can not carry electricity are
   called insulators they do not conduct
   electricity
2. Wood, plastic, glass and rubber are all
   insulators.

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Insulators and Conductors both have important Uses

• Wires are coated in plastic electricity cant
  flow through it so you dont get a shock if you
  touch it
• Copper wire allows electricity to flow through
• A plug has metal pins conduct electricity,
  insulated flex and a plastic cover to hold

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Electricity can be dangerous

• You shouldnt tough anything electrical with wet
  hands and that includes switches.
• Electricity can be conducted through sweat (salty
  water) to your body, giving you and electric
  shock
• Remember water conducts electricity