For many solids, expansion is directly proportional to temperature change.
Δℓ = αℓ0ΔT
Areas expand twice as much as lengths do.
ΔA = 2αA0ΔT
Volumes expand three times as much as lengths do.
ΔV = 3αV0ΔT
- expansion gap/joint
- anti-scalding valve
- bimetallic strip, thermostat
- expansion of holes (mounting train tires)
- "What's more, the aircraft expands by 15-25 centimeters during flight because of the scorching heat created by friction with air. Designers used rollers to isolate the cabin from the body, so that stretching doesn't rip the plane apart." Helen Pearson "Concorde wings its way into retirement." Nature Physics Portal. October 2003.
- "Concorde measures 204ft in length - stretching between six and ten inches in-flight due to heating of the airframe. She is painted in a specially developed white paint to accommodate these changes and to dissipate the heat generated by supersonic flight." source
- Thermal expansion is a small, but not always insignificant effect. Typical coefficients are measured in parts per million per kelvin (10−6/K). That means your typical classroom meter stick never varies in length by more than a 100 µm in its entire lifetime — probably never more than 10 µm while students are using it.
- length comparator
- push rod dilatometer (gives relative expansion, since the device itself expands)
- interferometer (highest precision method)
- x-ray diffactometer
- capacitance dilatometer
- strain gauge
- optical dilatometer (basically a digital camera)
- Some materials expand differently in different directions, notably graphite and wood (lumber).
Liquids can only expand in volume.
ΔV = βV0ΔT
Liquids have higher expansivities than solids.
β ~ 10−3/K, 3α ~ 10−5/K