The property of certain materials that enables them to return to their original dimensions after an applied stress has been removed. In general, if a stress is applied to a wire, the strain will increase in proportion (see OA on the illustration) until a certain point called the limit of proportionality is reached. This is in accordance with Hooke’s law. Thereafter there is at first a slight increase in strain with increased load until a point L is reached. This is the elastic limit; up to this point the deformation of the specimen is elastic, i.e. when the stress is removed the specimen returns to its original length. Beyond the point L there is permanent deformation when the stress is removed, i.e. the material has ceased to be elastic and has become plastic. In the plastic stages individual materials vary somewhat; in general, however, at a point B there is a sudden increase in strain with further increases of stress—this is the yield point. Beyond the point C, the breaking stress, the wire will snap (which occurs at point D).
Elasticity.
See modulus of elasticity.
A fundamental property of certain materials to retain energy during deformation caused by an applied force, with the release of the energy to allow the material to return to its original shape. Certain non-Newtonian fluids exhibit elasticity. For example, elasticity is seen as the energy that is retained in a fluid once a shear stress is removed causing a reversal of flow.
The ratio between the proportional change in one variable and the proportional change in another. The elasticity of variable y with respect to x is ε = (dy/y)/(dx/x). The concept is useful because comparisons of proportional changes are independent of the units in which the variables, such as price or quantity, are measured. As (dy/y)/(dx/x) = d(log y)/d(log x), elasticity equals the ratio of changes in the logarithms of the two variables. See also arc elasticity; point elasticity.
- continuous wave
- continuous-wave radar
- continuum
- continuum hypothesis
- CONTOUR
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- contract
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- contracted-out((services))
- contractible space
- contractile root
- contractile vacuole
- contracting Earth hypothesis
- contraction
- contractional kink band
- contraction((in animal physiology))
- contraction limit