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: **
3cm,20.5cm
17.5cm
first i measured using a reg ruler it stated 0-7.2cm then i read on through the directions and using a doubly reduced ruler i obtained the 3-20.5 cm reading. that is a difference of almost 10 cm so i would say im looking at a +/- of .02 (because of the .3 difference in the first and final measurement).
** The basis for your uncertainty estimate: **
first i measured using a reg ruler it stated 0-7.2cm then i read on through the directions and using a doubly reduced ruler i obtained the 3-20.5 cm reading. that is a difference of almost 10 cm so i would say im looking at a +/- of .02 (because of the .3 difference in the first and final measurement).
** Positions of the ends of each rubber band, actual lengths of each when the chain supports 1 domino: **
3,20.5 10,27.5 10,26.8 10,27.2 10,27 10,27.1
end
17.5,17.5,16.8,17.2,17,17.1
6,5,4,3,2,1
.01
(all measurements are in cm)
** Distances between ends when supporting 2 dominoes **
17.8,18,17.4,17.4,17,17.2
this is the weight of 2 dominos
** Lengths when supporting 4, 6, ... dominoes: **
18,18.3,17.6,18.3,17.6,17.8
4 dominos
18.1,18.8,18,18.5,18,18.2
6 dominos
18.7,19.1,18.4,19,18.2,18.6
8 dominos
19,19.5,19.6,19.8,18.5,19
10 dominos
end
** Your table of force in Newtons vs. length in cm for all rubber bands **
17.5,17.5,16.8,17.2, .19
17.8,18,17.4,17.4, .38
18,18.3,17.6,18.3, .76
18.1,18.8,18,18.5, 1.14
18.7,19.1,18.4,19, 1.52
19,19.5,19.6,19.8, 1.90
end
the columns of my table represent the newtrons (force) applying force to my rubber bands increasing their length which i measured in cm to the accuracy of +/- .01cm
** Describe the graph of your first rubber band **
My graph of th efirst rubber band according to force(newtrons) and length(cm), is increasing at an increaing rate. the second rubber band is increasing at an increasing rate, the third is increasing at an increasing rate, the fourth and final graphed band is increasing at a constant rate followed by an increasing at a constant rate followed by an incr by increasing rate.
** The tension force in your first rubber band at length 9.8 cm: **
i have no idea that point is so far off my graph i have no idea how to estimate so low but ill say .001
You used a doubly-reduced ruler. This is good for precision, but since the spacing doubly-reduced rulers is about 41% that of standard rulers, you should be multiplying your lengths by .41 to get the lengths in actual cm.
An actual length of 9.8 cm would correspond to 9.8 / .41 = 21.5 on the doubly-reduced scale.
** The length of your first rubber band when tension is 1.4 N: **
18.4cm
** 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: **
.19,.38,.76,1.14,1.52,1.90
i dont believe i understand what it is that im to report on this part since these are the weights for my points on teh graph or the table.
The curve isn't expected to actually go through any of the data points. There are uncertainties in these measurements, and the curve should follow the trend of the data points, but should not go out of its way to actually go through any of these points.
** 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: **
17.5,17.8,18,18.1,18.7,19
is this where you want that the actual measure ment on a too scale ruler was
7.2,7.4,7.1,7.3,7.0,7.3
** The typical error you estimate when predicting force for a given length from your graphs: **
the values in the curve are more allowing of some elbow room, but i prefer solidilty of my table but my measurements are on a doubly reduced ruler meaning the measurements arent real until you factor in the uncertainty percentage.
i'd say +/- .2 beacuse thats the amount of give in one newtron. and i still dont really understand how to factor in the uncertainty.
** The typical error you estimate when predicting length for a given force from your graphs: **
+/- .1cm because my doubly reduced measeurement is 17.5 my real measurement is 7..2 and if you factor you could drop the 10 and are left with 7.5.
Im sure that makes no sense
** **
1 and a half hours.
** **
i need help on the factoring of the level of uncertainty
To estimate the uncertainties, look at how far your data points are from the smooth curve. See my note above, and review the instructions in the experiment for sketching the curve. If the points are plotted carefully and the curve sketched as instructed, there will be discrepancies between the points and the curve, and since these discrepancies arise from experimental uncertainties, they give you a good idea of about how much uncertainty there is in your measurements.
In any case, your work is good. See my notes and let me know if you have questions.