Definition
Thermal Expansion is the tendency of matter to change in volume, area, or shape in response to a change in temperature.
Why It Matters
It must be engineered into bridges, railroads, and pipelines to prevent buckling.
Core Concepts
- Specific Heat (Thermal Inertia): Different substances “resist” changes in temperature differently.
- Thermal Expansion: Most materials expand when heated because their molecules move faster and push further apart.
- The Anomaly of Water: Water is most dense at . As it cools from to , it actually expands because it begins forming open-structured ice crystals.
- How to read: “Water is densest at four degrees Celsius; between four and zero degrees it expands instead of contracting.”
- Meaning: Unlike most liquids, water’s volume increases as it approaches freezing. Ice is less dense than liquid water, so it floats and lakes freeze from the top down. This is why ice floats and lakes freeze from the top down.