Your 'pearl pendulum' 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 general comment, if any: **
** Your description of the rhythm of the pendulum when tilted 'back' **
The sounds get closer together, I used the timer to time the sounds and they are at smaller and smaller intervals as time goes by, until it rests.
** Your description of the rhythm of the pendulum when tilted 'forward' **
The sounds get further apart this time as the ball has further to travel on both extremes. The timer shows that the intervals increase until the ball rests again.
** Your description of the process used to keep the rhythm steady and the results you observed: **
My set up is a little different but I adjusted the tape that is holding the ball through a small hole suspended over a large CD holder. I adjusted the ball until it was just barely resting on the contact point. The data points that I got were all were within .0001 of the average .343 and I got 13 hits.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
All phase differences based on 13 hits.
Avg = average time between 13 hits
Avg Deviation= the average time that deviates from the overall average of the time of the swings
Position 0
Avg 0.341796883
Avg Deviation 0.00077184 Almost negligible
Position 1 45 degree counter clock rotation
Avg 0.345703133
Avg Deviation 0.004497182
Position 2 90 degree counter clock rotation from position 0
Avg 0.236328133
Avg Deviation 0.004027049
Position 3 135 degree counter clock rotation from position 0
Avg 0.226236983
Avg Deviation 0.004339747
Position 4 180 degree counter clock rotation from position 0
Avg 0.218424483
Avg Deviation 0.005209498
Position 5 225 degree counter clock rotation from position 0
Avg 0.215820317
Avg Deviation 0.004397392
Position 6 270 degree counter clock rotation from position 0
Avg 0.247070317
Avg Deviation 0.004397392
Position 7 315 degree counter clock rotation from position 0
Avg 0.345703133
Avg Deviation 0.000415802
Postition 0 Back to original
Avg 0.359765633
Avg Deviation 0.000159861
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
Make sure the ball is just barely resting on the striking point to acquire the smallest changes in sound frequency. With this approach i got an average of .0001598 time deviated from the average time. That is very accurate.
** Your report of 8 time intervals between release and the second 'hit': **
Trial #1 .484
#2 .453
#3 .468
#4 .437
#5 .449
#6 .437
#7 .468
#8 .458
These numbers are the time it takes from the extreme release point until the 2nd strike of the pendulum.
Avg= .458 Avg Deviation= .00026
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
.5934,.6875,.6875,.6675
.5975,.6875,.6875,.6367
.5876,.6835,.6715,.6718
.5675,.6679,.6875,.6718
The first time in each line is from the release point until the second hit, then the other three are the times between the second and fourth and sixth and eighth hits of the pendulum. They are very consistent around .6875. I just timed the second hit then the fourth and so on with the timer.
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
12 cm
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
.5865,.6816,.6543
** Your description of the pendulum's motion from release to the 2d hit: **
When the pearl is released from the extreme point and strikes the bracket at its resting spot which is also the equilibrium it is not affected at all by the opposite extreme point because it can't physically get there because of the bracket.
** Your description of the pendulum's motion from the 2d hit to 4th hit: **
The motion of the first hit from release is only one path while from the first strike until the second there is two paths so it takes longer.
** Your description of the difference in the pendulum's motion from release to the 2d 'hit', compared to the motion from the 2d 'hit' to the 4th hit: **
Again there is one less path to travel when release from the extreme point already. The second and fourth there are four paths instead of just three.
Very good. There are four quarter-cycles vs. three quarter-cycles.
This is reasonably consistent with your timing results.
** Your description of the difference in the pendulum's motion from the 2d to the 4th 'hit' compared to the motion from the 4th to 6th hit: **
The applied energy is beginning to diminish and the motion is shorter, yet still takes the same time.
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
If this is from the release because of the starting point it only has one path to strike then the other strikes have to travel in both directions before the next strike.
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
I would expect them to decrease as the energy dissipates and the path traveled gets shorter, it seems the ball would take a shorter time to strike. However the acceleration of the ball is dependent decreases at the same time the applied force does making the time intervals the same.
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
If the length of the pendulum is shortened then the time intervals of the strikes become more frequent. This is a tell sign that the distance it swings is shorter since the acceleration of the ball should remain constant.
** **
1.5 hours
** **
My set up was somewhat different but I feel the results were accurate to the information you were looking for.
Very good work. See my note.