phy201
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): **
** #$&* first line ruler markings, distance in actual cm between ends, how obtained: **
1cm, 5.0cm
3.3 cm
I obtained these number using one of the paper rulers, the first is the measurement of the first rubber band marked 1 from one end to the other end, the second number is the distance from the end of the first rubber band to the beginning of the second rubber band. I beleive the uncertainty to be within of .1 of a cm.
** #$&* The basis for your uncertainty estimate: **
Because of the marking on the ruler, I can see the point were the rubber band ends.
** #$&* Positions of the ends of each rubber band, actual lengths of each when the chain supports 1 domino: **
1cm, 5.0cm
1cm, 5.1cm
1cm, 5.0cm
1cm, 4.9cm
1cm, 5.1cm
1cm, 4.9cm
End
3.3cm, 3.8cm, 3.2cm, 3.1cm, 3.2cm
1-2, 2-4, 4-5, 5-6
uncertainty of .1 cm
If the ends of the first rubber band are at 1.0 cm and 5.0 cm, then its length is 4.0 cm, not 3.3 cm. Not sure how you got your lengths.
** #$&* Distances between ends when supporting 2 dominoes **
1cm, 5.2cm
1cm, 5.4cm
1cm, 5.2cm
1cm, 5.3cm
1cm, 5.2cm
1cm, 5.3cm
These are the measurements of the rubber bands with the weight of two dominoes.
** #$&* Lengths when supporting 4, 6, ... dominoes: **
5.7cm, 5.8cm, 5.6cm, 5.8cm, 5.6cm, 5.7cm
4
6.0cm, 6.3cm, 6.2cm, 6.3cm, 6.3cm,6.1cm
6
6.6cm, 6.9cm, 6.7cm, 6.8cm, 7.0cm, 6.7cm
8
End
This is the data of 4 six and 6 dominoes, I stopped at eight dominoes becuae my weakest rubber bands had reached more than 30% of their original length
** #$&* Your table of force in Newtons vs. length in cm for all rubber bands **
5.0cm, 5.1cm, 5.0cm, 4.9cm, 5.1cm, 4.9cm, .19
5.2cm, 5.4cm, 5.2cm, 5.3cm, 5.2cm, 5.3cm, .38
5.7cm, 5.8cm, 5.6cm, 5.8cm, 5.6cm, 5.7cm, .76
6.0cm, 6.3cm, 6.2cm, 6.3cm, 6.3cm, 6.1cm, 1.14
6.6cm, 6.9cm, 6.7cm, 6.8cm, 7.0cm, 6.7cm, 1.52
Lengths look Ok here. Not sure what happened earlier, but you're OK now.
The rubber bands should actually be longer than reported; possibly you used different rubber bands or you used a printed-out ruler that printed too long. Not a problem, as long as you use the same-sized ruler for subsequent experiments.
End
each column above is the lenght of the rubber bands 1, 2, 4, 6, & 8
(columns are in that order 1 being the first column 8 being the fifth column) after the dominoes have been placed in the bags. at the end of each column is the total downward force exerted by gravity by the dominoes. So for the first column the lengths are for 1 dominoe with a force of .19, the second is the lenght after two dominoes with a force .19*2=.38, third lenght after four dominoes .19*4 =.76and so on.
** #$&* Describe the graph of your first rubber band **
increasing at an increasing rate
increasing at an increasing rate
increasing at an increasing rate
Increasing at an increasing rate
increasing at an increasing rate
increasing at an increasing rate
End
I think that the force, on the vertical axis, put on the rubber bands was increasing by the addition of each domino, The length, on the horizontal axis was increasing due to the addition weight, So all of the graph show an increase at an increasing rate throughout.
Here is the table for Force vs Length of my rubber bands for the first four of one dominoe
5.7, .19
5.8, .38
5.6, .57
5.8, .76
I don't see a rubber band on your table that corresponds to these lengths. Your table looks fine; but here you're reporting a rubber band that doesn't change its length much and at one point actually gets shorter at the force increases.
Tables for the additional dominoes are in the same format with the force in the y column and the lenght in the x column of the table.
** #$&* The tension force in your first rubber band at length 9.8 cm: **
1.6 newtons
All of your rubber bands report forces greater near 1.6 Newtons when their lengths are still less than 7 cm. This isn't consistent with your table.
** #$&* The length of your first rubber band when tension is 1.4 N: **
9cm
All your rubber bands exert forces greater than 1.4 N before reaching length 7 cm.
** #$&* 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: **
.19, .30, .60, 1.10, 1.50
The estimate of the curve of my graph was estimated in between each data point, between the first and second, third and fourth, fift and sixth. The force estimated according to this is close to the actual force exerted on each rubber band. For rubber band number two it is .08 difference, for number three it is .16, number four, .04, and number five .06 difference.
** #$&* The lengths predicted for forces .19 N, .38 N, .76 N, 1.14 N, etc. by the curve for your first rubber band; the deviations of your actual observations from these predictions: **
5.0cm, 5.3cm, 5.7cm, 6.2cm, 6.8cm
0.0cm, .01cm, 0.0cm, 0.2cm, 0.2cm
** #$&* The typical error you estimate when predicting force for a given length from your graphs: **
I have more faith in the values that I created in my table because that data is from actual measurements and calculations of the force. The data taken from the graph is more of an estimate than the data in the table.
I think the uncertainty would be .1 of a percent. .1/6.8= .01 * 100 =.1 percent
** #$&* The typical error you estimate when predicting length for a given force from your graphs: **
The uncertainty of the length would be about .2 percent .01/5.3=.0018 * 100= .2 percent
** **
about 2hours
** **
Your data look reasonable but your conclusions don't seem to match your data. See my notes and see if you can explain the discrepancies.
&#Please see my notes and submit a copy of this document with revisions and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end). &#