Thermal expansion
In physics, thermal expansion is the tendency of solid objects to increase in length or volume when heated. The amount of expansion will vary depending on the material's coefficient of thermal expansion.
Gasses also undergo thermal expansion (or an increase in pressure). See the ideal gas law for more information.
Most materials expand when heated and contract when cooled. The amount a material expands or contracts is given by the formula: (Lfinal − Linitial) / Linitial = α(Tfinal − Tinitial) where α is the coefficient of thermal expansion in inverse kelvin.
In materials engineering, the three primary types of materials have well defined rates of expansion. Polymers expand as much as 10 times more than metals, which expand more than ceramics. Thermal expansion generally increases with bond energy. See PVT relation.