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# Elasticity

based on 11 ratings
Source:
Author: Janice VanCleave

### Purpose

To determine how elastic a gummi worm is.

### Materials

• Rubber band
• Scissors
• 4 gummi worms
• Metric ruler

### Procedure

1. From the rubber band, cut a section that is the same length as a gummi worm.
2. Place a gummi worm along the edge of a ruler. Measure the worm to the nearest 0.1 mm. Record this as the starting length in a Length Data table like the one shown.
3. Stretch the gummi worm as far as possible without breaking it, and record the greatest length as the stretched length.
4. Release the gummi worm, wait for it to stop contracting, and again measure its length. Record this as the final length
5. .
6. Determine any change in length by finding the absolute difference between the starting and final lengths. This is done by subtracting the smaller value from the larger one.
7. Repeat steps 2 to 5 with the remaining gummi worms and the section of rubber band.

### Results

The results vary. The author found the final length of the gummi worms to be slightly more than their starting lengths and the rubber band's final length to be the same as its starting length.

### Why?

Elasticity is the ability of a material to return to its original shape after being stretched. A rubber band is generally considered perfectly elastic, meaning it returns to its original length after being stretched. The rubber band is used as the standard (a material against which other materials are compared) against which you are comparing the elasticity of the gummi worms. A gummi worm will generally contract to almost the same length at which it started. So the elasticity of the worm is great, but slightly less than that of the rubber band.

### FOR FURTHER INVESTIGATION

When some metals are heated, such as gold, they can be stretched into thin threads, but they do not return to their original shape. Could gummi worms be stretched into a thin thread if heated? A project question might be, How does temperature affect the elasticity of a gummi worm?

1. Repeat the investigation, changing the temperature of both the gummi worm and the rubber band. They can be heated by placing them in a plastic resealable bag and placing the bag in a bowl of warm water for a measured time. Cool them by placing the bag in a bowl of icy water, refrigerator, and/ or freezer for a measured time.
2. Take photographs of the starting, stretched, and final gummi worms and rubber bands. Display the photographs along with samples of the gummi worms and rubber bands used.

### REFERENCES AND PROJECT BOOKS

Bonnet, Robert L., and Dan Keen. Science Fair Projects with Electricity and Electronics. New York: Sterling, 1996.

Graf, Rudolf F. Safe and Simple Electrical Experiments. New York: Dover, 1964.

Hann, Judith. How Science Works. Pleasantville, N.Y.: Reader's Digest, 1991.

Jones, Mary, and Geoff Jones. Physics. New York: Cambridge University Press, 1997.

Murphy, Pat, Ellen Klages, and Linda Shore. The Science Explorer. New York: Owl Books, 1996.

Potter, Jean. Science in Seconds for Kids. New York: Wiley, 1995.

Science in Seconds with Toys. New York: Wiley, 1998.

VanCleave, Janice.janice VanCleave's A+ Projects in Chemistry. New York: Wiley, 1993.

janice VanCleave's Molecules. New York: Wiley, 1993.