both cases of increasing and decreasing the hanging weights; the strain is almost the same for the same stress, so the Young’s Modulus is the same for the both cases. This phenomenon was observed and is reflected in the data tables 1 and 2. For example in table 1 (adding weight) for 4 kg the stress is 9.63*10 7 (N/m 2 ) and the strain is 0.000427, and when viewing table 2 (removing weight) the stress and strain values are the same for 4 kg. 2. In both plots, some of the data point falls in a straight line. Some factors that would cause the deviation from a straight line would be not accurately measuring ΔL and L (human error), and also the precision and reliability of the lab equipment. 3. If the wire is replaced with one twice as thick, the new value of stress would be ½ less than its original value, because the same force (F) is being divided by an area (A) twice the original value. The relationship between stress and area are inversely proportional. The new value of Young’s Modulus would be half of its original value as well. (Please see attached calculation and graph sheet) 4. Yes, it does make significant difference whether you measure the diameter and the length of the wire at the beginning (with only 1kg), or when there are 7kg total loaded
on the hook because when one puts 7kg weight on the hook, the wire stretches and its diameter decreases. Conclusion: This lab demonstrated how to find by physical experimentation the Young’s Modulus of elasticity of a thin wire by adding 7 kg of mass ( 1 kg at a time) to the wire in order to stretch it. As a result of this lab, one can find the Young’s Modulus by plotting the Stress vs. Strain on graph and then determining the slope of the line produced. It can be seen by the slope calculation of the graphs produced for table 1 and table 2 that the slopes are equal.
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