Fracture Stress Test Devon O’Connor9 th Grade

What is the effect of temperature on the elasticity of different materials? Problem Reasoning Bird feeder Expansion joints in bridges

Research ColdRoom Temperature Hot RubberStrongModerately weak Weak StringStrongModerately strong Weak MetalModerately strong StrongModerately weak WoodStrongWeak Hooke’s Law: - the extension of a spring is in direct proportion with the load added to it, as long as this load does not exceed the elastic limit

If materials are heated, then they will break more easily. Hypothesis

Rubber bands of varying widths – 6 wide (about 1 cm wide), 6 skinny (about ½ cm wide) Toothpick – 6 Copper Wire – about 60 cm Yarn – about 90 cm Scissors Incubator Refrigerator Force Meter Materials

Procedure: A copy of each material was placed in a temperature controlled area. (One copy at room temperature, a second in an incubator, and a third in a refrigerator) The materials were left for twenty-four hours. The materials were removed and, one by one, attached to the force meter. Each material was pulled downward until broken. The amount of force needed to break each material was measured. Conclusions were drawn. The procedure was repeated. Controls: The controls are the materials at room temperature. Constants: The constants are the types of materials, the incubator, the refrigerator, and the force meter. Independent: The independent variables are the temperatures to which the materials are subjected. Dependent: The dependent variable is the elasticity of the materials. Procedure

Data WireRefrigerator Room TemperatureIncubator Trial Trial Avg STDEV

Data Thin Rubber BandRefrigerator Room TemperatureIncubator Trial Trial Avg STDEV

Hypothesis If materials are heated, then they will break more easily. Supportive or Not Wire breaks more easily when heated. The rest of the results are inconclusive. Conclusion

If hanging a lamp inside, then it is better to use string, wire, or wood rather than rubber. If the lamp was being hung outside in the winter or the summer, then there is no true difference between any of the materials’ strengths. Conclusion What Went Wrong Flaws in the materials may have affected the results. Improvements Be more exact about the amount of time allotted in the incubator or refrigerator More precise measurements of the materials Carrying Further See if the lengths of the materials affects its fracture stress

Kauffman, George. “Rubber.” Chemistry Explained. N.p., n.d. Web. 7 Nov “Rubber Bands and Heat.” University of Wisconsin-Madison. N.p., n.d. Web. 7 Nov “Solids.” Ultimate Visual Dictionary of Science Print. VanCleave, Janice. Guide to the Best Science Fair Projects. New York: Scholastic, Print. “Strength-Toughness.” September University of Cambridge Department of Engineering. Materials Group. “Strength-Max. Service Temperature.” September University of Cambridge Department of Engineering. Materials Group. Thank You! Questions?