![]() The equation σ = Ee is known as Hooke’s law and is an example of a constitutive law. The value of E depends on the material the ratio of its values for steel and rubber is about 100,000. In other words, σ is proportional to e this is expressed σ = Ee, where E, the constant of proportionality, is called Young’s modulus. In a simple tension test, the elastic response of materials such as steel and bone is typified by a linear relationship between the tensile stress (tension or stretching force per unit area of cross section of the material), σ, and the extension ratio (difference between extended and initial lengths divided by the initial length), e. The mathematical theory of elasticity and its application to engineering mechanics is concerned with the macroscopic response of the material and not with the underlying mechanism that causes it. By contrast, at the microscopic level, rubberlike materials and other polymers consist of long-chain molecules that uncoil as the material is extended and recoil in elastic recovery. Under stress the atomic bonding can be broken at quite small deformations. The elasticity of steel and other metals arises from short-range interatomic forces that, when the material is unstressed, maintain the atoms in regular patterns. The different macroscopic elastic properties of steel and rubber result from their very different microscopic structures. The elastic properties of many solids in tension lie between these two extremes. Steel is much stronger than rubber, however, because the tensile force required to effect the maximum elastic extension in rubber is less (by a factor of about 0.01) than that required for steel. The elastic limit depends markedly on the type of solid considered for example, a steel bar or wire can be extended elastically only about 1 percent of its original length, while for strips of certain rubberlike materials, elastic extensions of up to 1,000 percent can be achieved. What force slows motion? For every action there is an equal and opposite what? There’s nothing E = mc square about taking this physics quiz. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today. ![]()
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