Rubber bands

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Ali_1
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#1
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#1
hbjn
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nevetstreblig
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#2
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#2
Elastic bands do NOT obey hooke's law. As the force applied is NOT proportional to the extension of the band. Typically, a fair amoutn of stress is required on stretching to produce a small amount of strain...but eventually, less stress is needed for the same amount of strain. This is because the atoms/bonds in the elastic band have more kinetic/heat energy so can be extended further.
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Stonebridge
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#3
Report 10 years ago
#3
(Original post by Ali_1)
Hi,
I was just really confused on the properties of rubber bands, basically do they obey Hooke's law or not? And when they are heated - do they extend more than usual or less?
Thanks in advance guys,
Ali
As #2 above states, they do not obey Hooke's Law.
They stretch more easily at first as the long chain molecules start to untangle. Eventually they become stiffer as the chains are fully extended.
If you increase the temperature you increase the disorder in the long chain molecules. This means their resistance to being aligned also increases.
Consequently the value of the modulus E increases with temperature. In other words the material is more difficult to stretch.
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chocochocoloco
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#4
Report 4 years ago
#4
where did you find this out from
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