Friday, February 26, 2010

Heat and its Effects

Heat changes the size of a substance.

Heat - substance expands
Cool - Substance contracts

Solids
Examples: Metal ring and ball

Liquids
Examples: Glass flask containing coloured water
- Hot water
   + Liquid level rise
- Cold water
   + Liquid level drop

Gas
Examples: empty flask containg air and a drop of coloured water
- Hot hands/water
   + Coloured waster rises
- Iced water
   + Coloured water dropped

Problems

Problem
- Cause pavements to crack/ tiles pop out
Solution
- Expansion gap

Problem
It's the closest I can get
- Railway tracks wrap
Solution
- Gaps in between tracks

Problem
- Bridges expand, and may be at risk of damage
Solution
- Expansion gaps or resting on rollers

Problem
- Expansion of water pipes/ oil pipelines, causing them to burst
Solution
- Expansion bends

Problem
- Telephone wires/ cable contract in cold weather, and become taut, any may snap
Solution
- Wires are strung loosely

Uses of expansion
Riverts
- Join steel plates and girders
- Bimetallic strip
  + Thermostat
  + Thermometer

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