. THERMAL EXPANSION

6. THERMAL EXPANSION
Key notes:
1. Solids expand when heated and contract when cooled.
2. Different solids of the same volume expand by different amounts when heated
through the same increase of temperature.
3. A large force is set up when a solid is expanding or when a solid is
contracting.
4. Applications of thermal expansion include thermostats, fire alarms, bimetallic
thermometers, fixing rivets and fitting axles to flywheels.
5. To avoid damage to concrete roads, metal bridges, telephone cables and steam
pipes due to temperature changes, allowance must be made for expansion and
contraction to occur.
6. When the same volume of a liquid and a solid are heated through the same
increase in temperature, the liquid expands more than the solid.
7. Different liquids of the same volume expand by different amounts when
heated through the same increase in temperature.
8. Water contracts when its temperature increase from 0 °C to 4 °C.
9. The density of water is greatest at 4 °C.
10. Ice floats on water with 10% of its volume above the water surface.
11. Gases expand much more than solids or liquids when heated.
12. The density of a gas decrease when it is heated.