# Fast and Easy Science Fair Projects: Toy Story

Updated on December 30, 2019
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## Torque-energy storage in a homemade toy

Purpose: Determine the optimum (best) number of band windings for an ice-pop toy.

Overview: This simple old-time homemade toy demonstrates three concepts of physics potential energy, torque, and elasticity. A stick is placed inside the loop of a rubber band and turned, so the band is wound up. The wound band has "potential" energy, that is, stored energy thatm when released, becomes "kinetic" energy. As with the whirring button in Project 41, the concept of "torque." a twisting force, is also demonstrated.

The more a rubber band is twisted, the more potential energy it can store. But is there a point where additional winding does no more good, or can even be bad?

Hypothesis: A certain number of elastic band turns with give consistently best results.

You need:

• 3 ice-cream pop sticks
• Rubber band
• Hardbound book

Procedure: Hold one ice-cream stick in each hand and place the rubber band around them. In the middle of the rubber band, place a third stick.

Turn the center stick, winding the rubber band tighter and tighter. Count the number of turns. After it is wound many times, carefully place the toy under a book on a table. Lift up the book and the toy will dance.

Wind the tou again, this time making five more turns than before. The elastic band and the sticks are Constants, the number of turns is the Variable. Does the toy dance better with the extra twists?

Experiment by adding more and more windings. Is there a limit to the torque energy stored in the elastic band beyond which there is no benefit?

Results and Conclusion: Write down the results of your experminet. Come to a conclusion about your hypothesis.

Something more: At what point does the toy have potential energy? Kinetic energy? What effect does using different rubber bands (longer or thicker) have on the energy stored? (For fun, surprise family and friends, dancing torque toys of all sizes!)

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