Phy 231
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: **
10.00 cm, 17.15 cm
7.15 cm
I found the numbers by putting the 10 cm mark on the rule at the very top of the rubber band and with the human eye i found the bottom value which i found to be 17.15 cm. I think this measurement is accurate to +- 0.05 cm because i am confident in the fact that the value is at least accurate to the tenths place. This was rubberband number 1.
** #$&* The basis for your uncertainty estimate: **
I had to measure it by what my eyesight thought it was and it is known that the human eye is not 100% accurate. There definitely may have been room for human error.
** #$&* Positions of the ends of each rubber band, actual lengths of each when the chain supports 1 domino: **
10.00 cm, 17.15 cm
10.00 cm, 17.23 cm
10.00 cm, 17.29 cm
10.00 cm, 17.48 cm
10.00 cm, 17.21 cm
10.00 cm, 17.09 cm
End
7.15 cm, 7.23 cm, 7.29 cm, 7.48 cm, 7.21 cm, 7.09 cm
1,2,3,4,5,6
The uncertainty is once again +-0.05 cm.
** #$&* Distances between ends when supporting 2 dominoes **
7.15 cm, 7.43 cm, 7.33 cm, 7.84 cm, 7.38 cm, 7.10 cm
These are the results from the weight of two dominoes.
** #$&* Lengths when supporting 4, 6, ... dominoes: **
7.43 cm, 7.56 cm, 7.42 cm, 7.89 cm, 7.55 cm, 7.32 cm
4
7.60 cm, 7.82 cm, 7.61 cm, 8.10 cm, 7.73 cm, 7.44 cm
6
7.79 cm, 8.09 cm, 7.91 cm, 8.42 cm, 7.81 cm, 7.82 cm
8
8.11 cm, 8.29 cm, 8.15 cm, 8.69 cm, 7.90 cm, 7.91 cm
10
End
** #$&* Your table of force in Newtons vs. length in cm for all rubber bands **
7.15 cm, 7.23 cm, 7.29 cm, 7.48 cm, 7.21 cm, 7.09 cm (1 domino, 0.19 N)
7.15 cm, 7.43 cm, 7.33 cm, 7.84 cm, 7.38 cm, 7.10 cm (2 dominoes, 0.38 N)
7.43 cm, 7.56 cm, 7.42 cm, 7.89 cm, 7.55 cm, 7.32 cm (4 dominoes, 0.76 N)
7.60 cm, 7.82 cm, 7.61 cm, 8.10 cm, 7.73 cm, 7.44 cm (6 dominoes, 1.14 N)
7.79 cm, 8.09 cm, 7.91 cm, 8.42 cm, 7.81 cm, 7.82 cm (8 dominoes, 1.52 N)
8.11 cm, 8.29 cm, 8.15 cm, 8.69 cm, 7.90 cm, 7.91 cm (10 dominoes, 1.90 N)
** #$&* Describe the graph of your first rubber band **
The graph is increasing at an increasing rate. This is because the force of each rubber band grew and that value changed at a different value every time. It is hard to explain about each line separately because the values are all very close.
End
** #$&* The tension force in your first rubber band at length 9.8 cm: **
3.04 N
** #$&* The length of your first rubber band when tension is 1.4 N: **
7.88 cm
** #$&* The forces at your observed lengths the 1st rubber band, as given by the curve, and the deviations of those curve-predicted lengths from the observed lengths: **
2.3 N, 2.4 N, 2.6 N, 2.7 N, 2.8 N
The estimate of the curve differs from the actual weight supported because these are not exact values.
** #$&* 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: **
0.19 N, 0.38 N, 0.76 N, 1.14 N, 1.52 N, 1.90 N
The forces were exactly the same as what i made them out to be.
** #$&* The typical error you estimate when predicting force for a given length from your graphs: **
I would have more faith in the table because they were actual set points rather than possible points which can be found using a graph. There would have been a great amount of uncertainty because it is a graph and it is hard to get an accurate precise value.
Given the uncertainty you mentioned earlier in using your eye to make the measurements, one would expect each measured length to be a little greater or a little less than the actual length. Your data points would therefore be more or less randomly scattered about the actual force vs. length curve, and a curve that more or less 'goes through the middle' of your scattered data points would likely tend to 'smooth out' the unavoidable errors in your measurements.
** #$&* The typical error you estimate when predicting length for a given force from your graphs: **
I think the estimate would be not as big because i had an uncertainty of +- 0.05 before which would be the same uncertainty here.
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80 mins
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&#This looks good. See my notes. Let me know if you have any questions. &#