Home >> Science & Nature >> Science

How to Accurately Measure the Elasticity of a Rubber Band

Elasticity is the ability of a solid object to be deformed through stress and return to its original size when the stress has been removed. All materials have some elasticity. Natural rubber, such as that found in rubber bands, is highly elastic. However, a rubber band will remained deformed once it reaches the elastic limit. Measuring elasticity uses Hooke's law, which states that deformation is proportional to the stress applied to the object. This will determine the amount of force required to reach the elastic limit of the rubber band.

Things You'll Need

Scissors
Skewer
Tape
Jar
Ruler
Weights

Instructions

- 1
  Cut the rubber band so that it is no longer a circle. Examine the rubber band to verify that there are no cracks in the band that will affect the results.
- 2
  Wrap one end of the rubber band around the middle of a wooden or bamboo skewer and tape it to hold it in place.
- 3
  Place the skewer across a space that allows the rubber band to dangle and extend when weights are added. A tall jar or two stacks of books placed close together will work. Roll up more of the rubber band to shorten the hanging end if necessary.
- 4
  Place a ruler, standing vertically, next to the rubber band apparatus. Record where on the ruler the bottom of the rubber band is located.
- 5
  Add hooked weights to the end of rubber band in 50-gram increments. Let the weight pull down the rubber band and record where the bottom of the rubber band is located on the ruler.
- 6
  Remove the weights after each trial to see if the rubber band goes back to its original size. Once the rubber band does not snap back after removing the weight, the elastic limit of the rubber band has been reached.
- 7
  Graph how the rubber band reacted during each trial, comparing the weight used and the change in rubber band length. For example, if the bottom of the rubber band started at zero and moved to the 2-inch mark when 50 grams were added, the rubber band moved 2 inches. As the weights increase, so will the distance from the starting point. This demonstrates the relationship between the weight applied and the amount of stretch in the rubber band.
- 8
  Convert grams to Newtons. The Newton is a measurement of force. 1,000 grams is equal to 9.8 Newtons. For example, if the rubber band required 500 grams to reach its elastic limit, it can withstand 4.9 Newtons of force, which is the measure of its elasticity.

Science