phy 201
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,7.2cm
7.2cm
i obtain this number by measuring the first rubber band with the ruler.i marked these rubber bands with a permanent marker by putting 1 line on the first one, 2 lines on the second one and so on.
** The basis for your uncertainty estimate: **
there could be some uncertainties in the process of measuring the lenght of the first rubber band that would be ruler inaccquracy, distractions during measurements, ruber band in satability etc.
** Positions of the ends of each rubber band, actual lengths of each when the chain supports 1 domino: **
1cm,7cm
7cm,14cm
14cm,21cm
21cm,28cm
28cm,35cm
35cm,42cm
END
7.2,7.2,7.2,7.2,7.2,7.2
1,2,3,4,5,6
uncertainty could be because of the inaccuracey of the measuring ruler, mistaken measurement by the performer, unstability of the rubber bands etc.
** Distances between ends when supporting 2 dominoes **
4.6cm,4.6cm,4,6cm,4.6cm,4.6cm, 4.6cm,
these result was from the weight of two dominoes.
** Lengths when supporting 4, 6, ... dominoes: **
7.5,7.8,7.7,7.6,7.6,7.6
4
7.6,8,8,7.9,7.7,7.7
6
7.9,8.3,8.3,8,7.9,7.9
8
End
** Your table of force in Newtons vs. length in cm for all rubber bands **
7.2,0.19N
7.3,0.19N
7.5,.19N 7.8,0.38N 7.7,0.57N 7.6,0.76N 7.6,0.95N 7.6,1.14N
4
7.6,0.19N 8,0.19N 8,0.19N 7.9,0.19N 7.7,0.19N 7.7,0.19N
6
7.9,0.19N 8.3,0.19N 8.3,0.19N 8,0.19N 7.9,0.19N 7.9,0.19N
8
** Describe the graph of your first rubber band **
From the data point it might appear that the force corresponding to 7.6 cm is about 1.14 Newtons. However we're going to put our trust in the curve.
We project a line from the L = 7.6 point on the horizontal axis, straight up to the curve, then straight over to the F axis.
Reading the point on the y axis as F = 1.13 or maybe F = 1.15 we see that the curve gives us a force between 1.13 and 1.15 Newtons.
we believe that the curve is more reliable than our data points, and we will tend to believe this estimate more than our data point.
Similarly we use the curve to estimate the length that gives us a force of 2 Newtons.
We project a horizontal line from the F = 2 point on the vertical axis to the curve, then from this point we project vertically downward to the horizontal axis.
We read a length of about 8 cm. Again we use the curve, which 'averages out' the characteristics of several data points, to estimate the required length.
** The tension force in your first rubber band at length 9.8 cm: **
2.07
** The length of your first rubber band when tension is 1.4 N: **
7cm
** 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: **
8.7,0.19N 8.9,0.38N 9.3,0.57N 9.8,0.76N
not much.
** 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: **
7.5,.19N 7.8,0.38N 7.7,0.57N 7.6,0.76N 7.6,0.95N 7.6,1.14N
** The typical error you estimate when predicting force for a given length from your graphs: **
i have more trust on the data in the table the on the curve because in the curve all the values are found.
negative value would be the uncertain in the graph.
** The typical error you estimate when predicting length for a given force from your graphs: **
the negative value for the length would be the uncertain for the lenght on the graph.
** **
more then 3 hours.
** **
&#Good responses. Let me know if you have questions. &#