Linear Thermal Expansion

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Linear Thermal Expansion
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Normal Solids

• Ex. Glass jar too tight, hot water over lid.
• L length
• T temp.
• Length and temp. is directly proportional.

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Thermal Expansion

• Linear expansion increase in any one dimension
  of a solid, linear is the expansion occurring
  along a line.
• Change in length is proportional to both
  (initial) L and change in Temp.
• Proportionality constant a(alpha), is called the
  coefficient of linear expansion.

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Thermal Expansion

• Coefficient of linear expansion ___ has the unit
  of _____.
• Value of the ____ depends on the nature of the
  material.

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Coefficients of Thermal Expansion for Solids and
Liquids
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Expansion Joint
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Usefulness

• Anti-scalding device shuts off the flow of water
  when it becomes too hot,
• Higher temp expands the actuator spring and
  pushes the plunger forward, shutting off the
  flow.

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Homework Problem 5.

• If a 42 m steel footbridge experiences extreme
  temperatures between -12C and 40C, what is the
  range in size of this bridge if it measures
  exactly 42m at 22C? (Steel has a coefficient of
  linear expansion of 1.1x10 -5/C)

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Calculate Length for each set of values

• L1L(1a?T1) T1 -12-22-34
• 42(1 1.1x10 -5(-34))41.9843 m
• L2L(1 a?T2) T240-2218
• 42(1 1.1x10 -5 (18))42.0083
• ?LL2-L1 42.0083-41.9843.024024m