Phy 201
Your 'rubber band calibration' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Your initial comment (if any): **
** first line ruler markings, distance in actual cm between ends, how obtained: **
8.2cm, 15.1cm
6.91
I obtained the number in the 2nd line by actually holding my ruler up to the rubber band and measuring its length. The rubber band was just a sliver over 6.9cm, so I estimated its length to be 6.91cm.
** The basis for your uncertainty estimate: **
It was a little hard to measure the rubber bands. Since I was attempting to measure the lengths after I had hung the chain up, it was a little more difficult. The chain wasn't stable and and since my ruler only measured to decimeters, it was hard to give the length in millimeters.
** Positions of the ends of each rubber band, actual lengths of each when the chain supports 1 domino: **
8.2, 15.1
20.0, 26.6
31.3, 38.2
46.1, 52.7
57.4, 63.9
71.5, 77.6
END
6.92, 6.60, 6.96, 6.66, 6.51, 6.13
1, 2, 3, 4, 5, 6
Like I said above, the uncertainties are the same. I really have no idea how long these rubber bands are to the nearest 0.01cm.
** Distances between ends when supporting 2 dominoes **
7.23, 7.01, 7.15, 7.35, 6.48, 6.84
These results were from the weight of 2 dominoes.
** Lengths when supporting 4, 6, ... dominoes: **
7.40, 7.13, 7.47, 7.62, 7.33, 7.33
4
7.65, 7.48, 7.52, 7.81, 7.52, 7.52
6
7.81, 7.59, 7.82, 8.10, 7.71, 7.82
8
8.06, 7.88, 7.92, 8.20, 7.94, 8.01
10
END
** Your table of force in Newtons vs. length in cm for all rubber bands **
6.92, 6.60, 6.96, 6.66, 6.51, 6.13 - .19
7.23, 7.01, 7.15, 7.35, 6.48, 6.84 - .38
7.40, 7.13, 7.47, 7.62, 7.33, 7.33 - .76
7.65, 7.48, 7.52, 7.81, 7.52, 7.52 - 1.17
END
The data represented here before the hyphen represents the length (in centimeters) the 4 selected rubber bands were stretched when being pulled down by the dominoes. The data after the hyphen represents the actual amount of force (in Newtons) the Earth is exerting on the rubber bands through the dominoes.
** Describe the graph of your first rubber band **
From what I drew free-hand on my paper, it appears that the first rubber band's graph is increasing at a decreasing rate throughout.
The other graphs follow a very similar pattern as this first graph. They all have increasing slopes, but all share moments of increasing at increasing rates, and moments of increasing at decreasing rates.
END
** The tension force in your first rubber band at length 9.8 cm: **
I get an estimation of about 2.31 Newtons
** The length of your first rubber band when tension is 1.4 N: **
I get an estimation of about 7.2 cm.
** The forces at your observed lengths the 1st rubber band, as given by the curve, and the deviations of those curve-predicted lengths from the observed lengths: **
2.0, 2.2, 2.3, 2.4, 2.6, 2.7
There is not too much difference between these two measurements.
** The lengths predicted for forces .19 N, .38 N, .76 N, 1.14 N, etc. by the curve for your first rubber band; the deviations of your actual observations from these predictions: **
6.8, 7.2, 7.4, 7.8, 8.0, 8.2
.1, 0, 0, .1, .2, .2
** The typical error you estimate when predicting force for a given length from your graphs: **
I had more faith in the values from my table. Even though both had variable dgrees of estimation, I felt as though I could be more accurate with the measurements I took myself.
+/- 0.12 N
** The typical error you estimate when predicting length for a given force from your graphs: **
+/- 0.07cm
** **
This took me about 2 1/2 hours
** **
&#This looks good. Let me know if you have any questions. &#
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