Fracture Stress Test Devon O’Connor9 th Grade The Academy of Notre Dame de Namur

What is the effect of temperature on the elasticity of different materials?

Room Temperature: -Wood – brittle and weak -Rubber – moderately weak -String – moderately strong -Metal – tough and strong Heated: -Wood, rubber, and string – weak -Metals – moderately weak Cold: -Wood, rubber, and string – strong -Metals – moderately strong

If rubber materials are heated, then they will contract and break easily. If the other materials are heated, then they will expand and be difficult to break.

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

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 variable is the temperatures to which the materials are subjected. Dependent: The dependent variable is the elasticity of the materials.

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’ strength. -This may be because of flaws in the materials. Hypothesis If rubber materials are heated, then they will contract and break easily. If the other materials are heated, then they will expand and be difficult to break. Supported or Not Wire breaks more easily when heated. (not supportive) Thick rubber bands are harder to break when cooled. (supportive) The rest of the results are inconclusive. 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 it’s fracture stress

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