This report was posted on 6/26/07 with a note indicating that it had not been reviewed. The reviewed document is posted here. I apologize for the error; your file was one of eight files the were incorrectly posted.
** Your initial comment (if any): **
** first line ruler markings, distance in actual cm between ends, how obtained: **
Each rubber band was approximately 2.75 inches in length. To convert inches to centimeters you will use the conversion factoer 2.54 cm = 1 inch. Therefore, 2.75 in. * (2.54 cm / 1 inch) = 6.99 cm
6.99 cm is the measurement for each of the six rubber bands.
** The basis for your uncertainty estimate: **
Because the chain is at least partially elastic, when the domino is placed in the bag the chain actually bounces a little before I could take proper measurements when it came to rest.
** Positions of the ends of each rubber band, actual lengths of each when the chain supports 1 domino: **
0,2.75 Each of the rubber bands had the same measurement for this trial.
Because the chain is at least partially elastic, when the domino is placed in the bag the chain actually bounces a little before I could take proper measurements when it came to rest.
** Distances between ends when supporting 2 dominoes **
Measurements for rubber bands 1 and 2 are each 3.0 inches or 7.62 cm. Measurements for rubber bands 3 through 6 are each 2.75 inches or 6.99 cm.
** Lengths when supporting 4, 6, ... dominoes: **
4 dominoes: 3 inches or 7.62 cm per rubber band
6 dominoes: 3.25 inches or 8.26 cm per rubber band
8 dominoes: 3.25 inches or 8.26 cm per rubber band
10 dominoes: 3.75 inches or 9.53 cm per rubber band
END
** Your table of force in Newtons vs. length in cm for all rubber bands **
1 domino: 2.5 inches or 6.35 cm per rubber band
2 dominoes: 2.75 inches or 6.99 cm per rubber band
3 dominoes: 2.85 inches or 7.24 cm per rubber band
4 dominoes: 3 inches or 7.62 cm per rubber band
5 dominoes: 3.20 inches or 8.13 cm per rubber band
6 dominoes: 3.25 inches or 8.26 cm per rubber band
7 dominoes: 3.25 inches or 8.26 cm per rubber band
8 dominoes: 3.25 inches or 8.26 cm per rubber band
9 dominoes: 3.50 inches or 8.89 cm per rubber band
10 dominoes: 3.75 inches or 9.53 cm per rubber band
I actually made a table with three columns (the first one just for my reference) but the information is as follows:
Number of Dominoes: 1 - 10
Newtons (Downward force, y-axis) : .19,.38,.57,.76,.95,1.14,1.33,1.52,1.71,1.9
Centimeters: 6.35,6.99,7.24,7.62,8.13,8.26,8.26,8.26,8.89,9.53
** Describe the graph of your first rubber band **
With the exception of a couple of domino additions, the measurements for each rubber band were pretty much the same and increased at a similar rate with the addition of dominoes. So most of the graphs look like a back slash (/) and had a linear relationship. I would say the line is increasing at an increasing rate because as the force increases the length of the rubber band increases.
** The tension force in your first rubber band at length 9.8 cm: **
2.09 N is my estimated force of Newtons. If you look at the trends of the measurements and how much they increase and decrease. The above listed measurement is the next most likely corresponding data point.
** The length of your first rubber band when tension is 1.4 N: **
8.26 cm is my estimated length measurement because I have several data points that are very close to 1.4 and they all have the same length.
** 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: **
From the information given previously in the assignment (1cm = .19 Newtons) and the information from my own data I came up with the following forces: 1.653,1.691,1.767,1.862,1.919
(8.7 * .19 = 1.653, etc.)
Estimates are not too terribly different.
** 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: **
8.7,8.9,9.3,9.8,10.1
6.35,6.99,7.24,7.62,8.13,8.26,8.26,8.26,8.89,9.53
2.35,1.91,2.06,2.18,1.97
** The typical error you estimate when predicting force for a given length from your graphs: **
The values I reported in my table are probably the most accurate because I measured them myself, and I was very careful to take accurate measurements. The values just created are estimated, and I will always be more likely to trust something I've actually experienced in the lab as opposed to and educated guess (or estimate). I think my estimates would be within about a centimeter of what they should be.
** The typical error you estimate when predicting length for a given force from your graphs: **
My estimates tend to be within 1 cm of what they should be.
** **
It took approximately 1 hour and 30 minutes to complete this experiment.
** **
Your calibrations aren't completely accurate, but they will probably serve OK as a basis for subsequent use.
Each rubber band will have a different length vs. force profile--you can't obtain good information on a single rubber band by averaging lengths over all rubber bands. Also I believe that most of these rubber bands will begin exerting tension at lengths of around 7.5 cm, give or take a few mm; I don't think you will find significant tension at the lengths you reported under 7 cm.