What are some examples of thermal expansion?

Almost every substance (solid, liquid or gas) expands when heated because the atoms and molecules move faster and take up more space.

A 50-ft long iron railroad rail will get about 1 mm longer for each 10 degrees Fahrenheit that it is heated. Although that doesn't sound like a lot, the expansion of long continuous rails can cause buckling of the rails and results in about 40 trail derailments every year.

Some examples of thermal expansion include:

• When metal objects such as railroad tracks, bridges, or electrical wires expand and contract with changes in temperature.
• Expansion joints in concrete structures to accommodate thermal expansion and prevent cracking.
• Expansion of liquids in a thermometer causing the liquid to rise or fall with temperature changes.
• Expansion of gases in hot air balloons causing the balloon to rise as the air inside expands.
• Expansion of materials like rubber or plastic in automotive tires with changes in temperature.