Hines- 8 PS
/_____ pts
Name:_____________________
Elastic Relationships Lab
Date/class:___________________
Lab Partners:___________________________________________________
BW: Most students will agree that the longer they study for tests, the higher they score. In other words,
test grades seem to be related to the amount of time spent studying. If two variables are related, one
variable depends on the other. One variable is called the independent variable; the other is called the
dependent variable. If test grades and study times are related, what is the independent variable – the test
grades or the time spent studying?________________________________________________________
Explain why._________________________________________________________________________
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One of the simplest types of relationships is the linear relationship. In linear relationships, the change in
the dependent variable caused by the change in the independent variable can be determined from a
graph.
Objectives: In this experiment, you will _________________________________________________
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Equipment:
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Several heavy books
Metric ruler
2 plastic-coated wire ties, 10 cm and 30 cm long
Ring clamp and ring stand
3 rubber bands, equal lengths, different widths
Procedure:
1. Set up the ring stand, ring clamp, and books as shown
in Figure 1.
2. Choose the narrowest rubber band. Securely attach
the rubber band to the ring clamp with the 10-cm
Figure 1 (courtesy of
plastic-coated wire.
Glencoe/McGraw Hill)
3. Measure the unstretched width of the rubber band using mm. Record this
value in Table 1-1.
4. Measure the length of the rubber band using cm as it hangs from the ring clamp with 50 g. mass
(hanger only). Record this value in Table 1-1.
5. Add 100 g. to the hanger and measure the length of the rubber band as it hangs from the ring
clamp. Record this value in Table 1-1.
6. Continue to add mass in 100 g. increments measuring and recording rubber band stretch. Do not
measure 550 g. , 850 g. and 1000 g.
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7. Replace the rubber band with the next widest rubber band. Hypothesize how the stretching of
the wider rubber band will differ from that of the thinner one. Record your hypothesis in the
hypothesis section of the lab.
8. Repeat steps #3-6 for the second rubber band.
9. Replace the rubber band with the widest one and repeat steps #3-6 for the third rubber band.
Hypothesis I: How will the stretching of the 2nd (Medium width) Rubber band differ from that of the
thinner one. Explain why you think this.
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Hypothesis II: How will the stretching of the 3rd (Wide width) Rubber band differ from that of the
thinner one and the medium. Explain why you think this.
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Use table #1 to record all data.
Sketch below how your graph will look. Include labels and slope lines of the three different rubber
bands.
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Analysis questions. Answer each question in complete, well-thought out sentences, be sure to
incorporate the question within your answer. If your handwriting is questionable please type!!!
1. What do the graphs you have made describe? ____________________________________________
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2. What does the steepness of the slope line of the graph measure? _____________________________
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3. How is the steepness of each of the three trend lines related to the width of the rubber bands?
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4. How is the flexibility of the rubber bands related to their widths?_____________________________
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5. Discuss if your hypothesis was supported by the results or refuted (unsupported) by the results. Be
very specific.
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6. Explain how someone looking at your graph could determine the length of the unstretched rubber
band without measuring it?
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7. How could you use the stretching of one of the rubber bands to measure the mass of an unknown
object? Explain.
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8. Would a 100 g mass hung from a rubber band stretch the same amount on the moon as on Earth?
What if the experiment were done in the reduced gravity environment of the ISS? In a pool of water?
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Possible Lab Extensions: Write questions that you have that you could test. Design an experiment to
test your idea. Brainstorm ideas below. Then use the Experimental Design sheet to finalize your
Experimental Design.
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