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Stress and Strain: The Young Modulus
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The model for this section is unashamedly unsophisticated. Three spring arrangements are subjected to tensile forces.
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The load can be increased and extension noted. The images are reinforcing the idea that the three springs in parallel are a stiffer arrangement than three springs in series.
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The idea with the Young modulus is that the geometrical factors affecting how much a sample stretches for a given load are factored out, leaving just the dependence on the material’s atomic arrangement and force laws.
- The model suggests that a long sample will stretch more for a given load than a shorter sample. How is this done?
- The model also suggests that a sample of larger cross sectional area will stretch less for a given load than a thinner sample. How is this done?
- Make an argument which suggests why looking at the ratio of strain (extension per unit length) and stress (force per unit area) gives a k value independent of sample dimension, unlike the classic Hooke’s law, where k = load/extension.
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Download this Resource
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Package:
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Youngs.exe (332Kb)
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Contents:
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youngs.mdl, youngs.doc, series.bmp, spring2.bmp and parallel.bmp
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Instructions:
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Download the self extracting ZIP archive. Locate the file using Windows Explorer and double click. The self extractor will then start. The default installation path is C:\AP Revision. Having set the path press the Unzip button. After the files have been extracted change directory to C:\AP Revision. To start the model double click on youngs.mdl
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