The Effects of Heat

Expansion and ContractionWhen the temperature of a material increases, the particles move faster.

These particles tend to spread out more.

This causes materials to expand or spread out as they get hotter.

Expansion and ContractionThe opposite happens when the temperature of a material decreases.

Cool materials tend to contract – shrink.

The material’s particles tend to slow down and stay closer together.

Expansion and ContractionGases are affected most with changing temperature, but solids and liquids are affected too.

Water is the exception to this.

Water expands when frozen, unlike most other liquids that contract (shrink) when cooled.

* How is Expansion and Contraction Useful?Thermometers have liquid mercury or colored alcohol in them. The liquid expands or contracts with changes in temperature and moves up or down the tube. The position of the liquid in the tube gives the temperature.

* How is Expansion and Contraction Useful?The solid materials that make up a bridge or sidewalk expand when warmed. If the sections are assembled tightly on a normal day, the will expand against each other on very hot days. This expansion can cause cracks to form. To guard against this problem, engineers leave some space between sections and fill it with a flexible material.

* How is Expansion and Contraction Useful?