Thermal Expansion Magnitude of Expansion of Solids, Liquids and Gases Examples of Expansion...
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Transcript of Thermal Expansion Magnitude of Expansion of Solids, Liquids and Gases Examples of Expansion...
Thermal Expansion
Magnitude of Expansion of Solids, Liquids and Gases
Examples of Expansion
Relationship between pressure and volume at a constant temperature
Thermal Expansion
• When molecules are heated they move far apart from each other– This causes the material to expand
• Expansion– Increase in size of a material due to
added heat • When molecules are cooled, the
molecules, move closer to each other– This causes the material to contract
• Contraction– Decrease in size of a material due to
heat removed
Let us look at 3 videos on the example of expansion and contraction
Applications of Thermal Expansion
Bimetallic strip as thermometer
Applications of Thermal Expansion
Liquid Expansion as thermometer
Road expansion gaps
Applications of Thermal Expansion
Tyre Fitting
Thermal Expansion
• All materials expand– Solids have linear expansion
• Varies among materials– Liquids and Gases have volume
expansion• Varies among materials
• Gases expands more readily than gas
• When a materials changes from solid to liquid, volume does not change much
• When a liquid changes to gas, the volume expansion is about 1000 times more
Pressure of a Gas
• Pressure of a gas– Force per unit area– Force is due to collisions with the walls of the
container– Units: Nm-2 or pascal, Pa
Pressure and Volume of a Gas at Constant Temperature
• At constant temperature, what happens to the volume of the gas when the pressure increases?
• At constant temperature, what happens to the pressure of the gas when the volume decreases?
• Boyle’s LawPα1/VpV = constantp1V1=p2V2