PHY 121
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: **
0,6 1/2
6.5 cm
6.5 is how long the first rubber band measures to be. The rubber band is marked with a 1. +.04
** The basis for your uncertainty estimate: **
I don't know if I read the ruler right and if I did not, then I hope it would have been off by much.
** Positions of the ends of each rubber band, actual lengths of each when the chain supports 1 domino: **
0, 6 1/2
0, 7
0, 7
0, 7 1/2
0,7
0, 7 1/2
END
6.50, 7.00, 7.00, 7.50, 7.00, 7.50
1 2 3 4 5 6
.04
** Distances between ends when supporting 2 dominoes **
6.67, 7.50, 7.30, 7.80, 7.70, 7.40
These were the results from the weight of two dominoes.
** Lengths when supporting 4, 6, ... dominoes: **
7.50, 7.90, 7.50, 8.30, 8.00, 8.30
4
7.70, 8.10, 8.00, 8.30, 8.00, 7.90
6
7.70, 8.40, 7.50, 8.70, 8.10, 8.00
8
** Your table of force in Newtons vs. length in cm for all rubber bands **
6.5, 7.00, 7.00, 7.50, 7.00, 7.50- .19 Newtons
6.67, 7.50, 7.30, 7.80, 7.70, 7.40 -.84 Newtons
7.50, 7.90, 7.50, 8.30, 8.00, 8.30- 1.22 Newtons
7.70, 8.10, 8.00, 8.30, 8.00, 7.90- 1.6 Newtons
7.70, 8.40, 7.50, 8.70, 8.10, 8.00- 1.98 Newtons
END
Each column represents its appropriate length in centimeters to the marked rubber band. For example the first column is the lenghts of rubber band # 1.
** Describe the graph of your first rubber band **
increasing at an increasing rate, then decreasing at an increasing rate.
increasing at an increasing rate.
increasing at an increasing rate, then decreasing at an increasing rate.
increasing at an increasing rate then decreasing at a decreasing rate.
increasing at an increasing rate then decreasing at a decreasing rate.
decreasing at an increasing rate then increasing at an increasing rate. END
These descriptions lead me to suspect you reversed your axes. Force should be on the vertical axis, length on the horizontal. No need to change your graphs, just be aware of the convention when reading instructions in other labs.
** The tension force in your first rubber band at length 9.8 cm: **
2.36
** The length of your first rubber band when tension is 1.4 N: **
7.7 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: **
Lenghts- 6.5, 7, 7.5, 8
.20, 1.24, 1.67, 1.99
.19,1.22, 1.6, 1.98
.10, .10, .07, .10
** 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: **
6.5, 7, 7.5, 8, 8.5
.10, .10, .05, .10
** The typical error you estimate when predicting force for a given length from your graphs: **
I have more faith in the values in my table, because I am not sure how accurate my line is, but I know the accuracy of my measurements.
+.04 N
** The typical error you estimate when predicting length for a given force from your graphs: **
+.05 cm
As I was measuring the rubber bands I wouls accidentally move the ruler down as I was trying to see the measurement.
** **
2 hours
** **
Very good work, but see my notes related to the orientation of your graphs.