Phy 231
Your 'energy conversion 1' 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 optional message or comment: **
** How far and through what angle did the block displace on a single trial, with rubber band tension equal to the weight of two dominoes? **
.4, 10
The block moved .4 cm, and rotated approximately 10 degrees before coming to rest.
** 5 trials, distance in cm then rotation in degrees, with rubber band tension equal to the weight of two dominoes: **
.4, 10
.55, 0
.60, 0
.60, 0
.60, 0
The numbers listed in the first column are the values of 'ds for the block after release, and the values listed in the second column are the degrees the block rotated as approximated by the changes in lines running parallel to the block.
** Rubber band lengths resulting in 5 cm, 10 cm and 15 cm slides: **
.8, 1.1, 1.6
All values were within restrictions
The firs value shows the increase from equilibrium position of the rubber band length in cm to cause the block to move 5 cm. The second and third values indicate the same for the rubber band as necessary to move the block 10 cm and 15 cm correspondingly.
** 5 trials, distance in cm then rotation in degrees, with rubber band tension equal to the weight of four dominoes: **
1.3, 10
1.75, 5
1.90, 0
1.85, 0
1.95, 0
The values in the first indicate how far the block moved when the tension equivalent to 4 dominoes was applied to the rubber band. The second column indicates an approximation of how far the block rotated as it moved.
** 5 trials, distance in cm then rotation in degrees, with rubber band tension equal to the weight of six dominoes: **
5.9, 10
6.0, 10
6.7, 0
6.9, 0
6.8, 0
The values in the first indicate how far the block moved when the tension equivalent to 6 dominoes was applied to the rubber band. The second column indicates an approximation of how far the block rotated as it moved.
** 5 trials, distance in cm then rotation in degrees, with rubber band tension equal to the weight of eight dominoes: **
5.9, 10
6.0, 10
6.7, 0
6.9, 0
6.8, 0
The values in the first indicate how far the block moved when the tension equivalent to 8 dominoes was applied to the rubber band. The second column indicates an approximation of how far the block rotated as it moved.
** 5 trials, distance in cm then rotation in degrees, with rubber band tension equal to the weight of ten dominoes: **
10.1, 0
10.0, 0
9.75, 5
10.1, 0
9.6, 0
The values in the first indicate how far the block moved when the tension equivalent to 10 dominoes was applied to the rubber band. The second column indicates an approximation of how far the block rotated as it moved.
** Rubber band length, the number of dominoes supported at this length, the mean and the standard deviation of the sliding distance in cm, and the energy associated with the stretch, for each set of 5 trials: **
7.15, 2, .55, .0866, 0.0004275
7.40, 4, 1.75, .2622, 0.001425
7.65, 6, 3.33, .3154, 0.002375
7.90, 8, 6.46, .4722, 0.003325
8.1, 10, 9.91, .2247, 0.003420
I gave the energy values the unit of Joules. My rubber band length values were the 'ds values of the rubber band length added in cumulative to the original 7 cm length. The number of dominoes correspond to the 'ds values measured in the previous lab. The third and fourth column giving mean and standard deviations were determined by using the data program for the 'ds values found above for the sliding of the block. The final column gives the energy associated with each stretch as previously determined in the Force vs. Displacement lab.
** Slope and vertical intercept of straight-line approximation to sliding distance vs. energy, units of slope and vertical intercept, description of the graph and closeness to line, any indication of curvature: **
2716.5, -1.56
Unit for slope is cm/J. Unit for vertical intercept is cm.
Two of the data points cluster above the line, and the other three cluster below the line. The graph seems to indicate a curvature that opens upward, and the curve is increasing at an increasing rate.
** Lengths of first and second rubber band for (first-band) tensions supporting 2, 4, 6, 8 and 10 dominoes: **
2043.1, -1.77
Unit for slope is cm/J. Unit for vertical intercept is cm.
Two of the data points cluster above the line, and the other three cluster below the line. The graph seems to indicate a curvature that opens upward, and the curve is increasing at an increasing rate.
** Mean sliding distance and std dev for each set of 5 trials, using 2 rubber bands in series: **
.15, .2
.4, .5
.65, .65
.90, 1.0
1.1, 1.1
** Slope and vertical intercept of straight-line approximation to sliding distance vs. energy, units of slope and vertical intercept, description of the graph and closeness to line, any indication of curvature: **
1.06, .05477
3.29, .1140
6.43, .1605
10.45, .3841
14.77, .3271
** 1-band sliding distance and 2-band sliding distance for each tension: **
0.55, 1.06
1.75, 3.29
3.33, 6.43
6.46, 10.45
9.91, 14.77
** Slope and vertical intercept of straight-line approximation to 2-band sliding distance vs. 1-band sliding distance, units of slope and vertical intercept, description of the graph and closeness to line, any indication of curvature: **
1.445, .8414
The slope is unitless, and the y-intercept is in cm.
The points are close to the line with two above, two below, and one on the line itself. The points seem to be following a mostly linear relationship.
** Discussion of two hypotheses: 1. The sliding distance is directly proportional to the amount of energy required to stretch the rubber band. 2. If two rubber bands are used the sliding distance is determined by the total amount of energy required to stretch them. **
I believe this supports the hypothesis, because the sliding distance did increase with the addition of the second rubber band; therefore, we know that the additional distance must have been gained by the energy input of the second rubber band.
** How long did it take you to complete this experiment? **
4 hours
** Optional additional comments and/or questions: **
I don't mean to complain, but this lab was unusually long, and by the time I finished I felt like I had run a mental marathon. If you don't mind the suggestion, perhaps you could look into a method that allows the student to collect the data from an online simulator or something similar to reduce time spent on the lab.
In the past I've gotten a lot of flack from my fellow physics faculty in the system (and they are a very good group) about using videos instead of hands-on labs. However I've been seriously thinking about doing some sort of mix, so I'm already thinking along the lines of your suggestion.
In any case your work was very good.