Stretching Rubber Bands

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Stretching Rubber Bands

        Planning

Aim

        We have studied the effect of a stretching force on a steel spring. We are now asked to investigate what extent rubber bands behave like steel springs. Design and carry out an experiment to test rubber bands for their elasticity. At least, two types of rubber band are available; although you may ask for more if we require them.

Variables

Dependent – stretching force

Independent – extension

Fixed – width of band, type of band

I will be testing the extension of the band, by placing differing loads on it. The width and type of band will be kept the same by using the same rubber band throughout the experiment. This is to ensure a fair test.

Prediction

        I predict that the rubber band will act very similar to the steel spring. I think that the predicted graph will look like this: -

This graph is like this because the extension increases in proportion to the load, until point B. This is when the band has reached its elastic limit and snaps. Therefore the load it can take will be 0g. I also predict that each time the rubber band is stretched it will be slightly longer then it was previously. This is because rubber is a polymer, which has a very tangled structure. It looks like this: -

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Every time it is stretched the structure becomes less tangled, thus making it longer. For this reason, I believe for each set of results the extension will increase slightly.

Apparatus

  • Clamp and stand
  • Rubber band
  • 1g weights and holder
  • G clamp
  • Meter ruler
  • Mirror
  • Pin

Safety

        I will ensure that the following things happen, to ensure the experiment is safe: -

  • Safety glasses are worn while the rubber band is being stretched.
  • Rubber bands are handled carefully
  • Mirrors are handled carefully

Plan

        Set up the apparatus as shown in the diagram below: -

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