# Fast and Easy Science Fair Projects: Back in Shape

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Identical rubber bands (2)
Clothesline
Paper clips (2)
Milk Carton
Awl (or) Nail
Water

## The Characteristics of Elasticity

Purpose: The purpose is to find he effect of weathering and stretching on the elasticity of a rubber band.

Overview: One characteristic of a material is a measure of its "elasticity." Elasticity is the ability of a material to return to its original shape after it has been stretched or pressed together. Balloons and rubber bands are very elastic. Can you think of other examples?

Have you ever seen a rubber band wrapped around a newspaper or something else that has been outside for some time? Have you ever seen an old rubber band that has been wrapped around something in an attic for many years? Can you observe cracks in the bands? Are they able to be stretched? Do they snap back to a smaller shape?

Hypothesis: After a rubber band has been stretched and exposed to outdoor weathering elements for several days, the elasticity of the rubber band will be affected, and it will not return to its original shape.

You need:

• 2 identical rubber bands
• 2 paper clips
• Large empty milk carton
• Water
• Clothesline
• Nail or awl, to poke a small hole in the milk carton

Procedure: For this project, we'll need a devise to test the elasticity of material.

Gather two identical rubber bands, a large empty milk carton, and two paper clips. Lay the two rubber bands on top of each other to check that they are as equal in shape as possible. The rubber band will be our Constant. Our Variable will be to stretch one rubber band and expose it to weather, while the other will remain unstretched and indoors, protected from weathering.

Bend open the paper clips to make "S" shaped hooks. Carefully poke a hole in the top of a large empty milk carton, and insert a paper clip hook through it.

Hang another paper clip hook on an outdoor clothesline and drape a rubber band on the bottom part of the paper clip hook. Hang the milk carton on the rubber band using the paper clip hook in the carton.

Pour some water into the milk carton. This will create a weight to stretch the rubber band. We want to stretch the rubber bad a lot, but not to the breaking point. Since rubber bands are not all the same, we can't tell you how much water to add to the carton. (Science is not always like a food recipe!) Slowly add more water to the milk carton until it looks like the rubber band is well stretched, but not in danger of breaking.

Leave the rubber band stretching device handing on the clothes line for three or four days. then, carefully, take the device apart and remove the rubber band. Line it up next to the other identical one that you had put aside indoors and compare them. Has the stretched one changed shape? Is it able to completely return to it's original shape?

Inspect the stretched rubber band closely. Are you able to see any cracks, discolorations, or other signs of deterioration caused by the experiment?

Results and Conclusion: Write down the results of your experiment. Come to a conclusion as to whether or not your hypothesis was correct.

Something more: Can you use your stretching device to test the elasticity of other materials or objects?

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htodd 5 years ago from United States

Thanks for the nice post..