Your work on pearl pendulum 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 rythym gets faster as the pearl continues to hit the bracket.
Your description of the rhythm of the pendulum when tilted 'forward'
The sounds of the pearl hitting the bracket get farther apart as the pendulum swings. Then finally the pearl stops hitting the bracket all together and hangs slightly away from the bracket.
Your description of the process used to keep the rhythm steady and the results you observed:
I placed the bracket on a table but the rythym of the pearl continued to speed up. So I folded a piece of paper and placed in under the back of the bracket in order to tilt it forward just slightly. After a few minor adjustments, the rythym of the pearl became steady, only speeding up on the last few hits before it stopped bouncing. The pearl hit the bracket about 15 times.
Your description of what happened on the tilted surface, rotating the system 45 degrees at a time:
I placed my text face up and the top of the book away from me. Then I placed one domino under each top corner so that the book was tilted toward me slightly. Then then I set up the bracket with the pearl facing me and the base parallel to the sides. I drew back and released the pendulum. The rythym slowed down with each strike.
I then rotated the bracket counterclockwise by 45 degrees. I released the pendulum again, and again it slowed down.
Then I rotated the bracket counterclockwise again to be perpendicular to the sides and relased the pendulum. The rythym was fairly constant at this point.
I then rotated the bracket counterclockwise by 45 degrees once more. This time the rythym was faster as each hit occurred.
I then rotated the bracket so that the base was facing me and the pearl was facing the top of the book. When I released the pendulum, the rythym sped up. The frequency was the fastest at this position.
After rotating the bracket another 45 degrees, the rythym of the pendulum when released sped up again.
Then after another rotation the bracket was perpendicular to the side with the pearl on my left and the base on my right. When I released the pearl, the rythym was relatively constant.
I rotated the bracket another 45 degrees and released the pendulum. This time the rythym was slower.
Finally, I returned the bracket to its original position. The rythym of the pendulum was the slowest at this position.
Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm:
To obtain the most steady beat of the pendulum I would set the bracket perpendicular to the sides and parallel to the ends.
Your report of 8 time intervals between release and the second 'hit':
.297
.297
.313
.297
.313
.297
.313
.313
Your report of 4 trials timing alternate hits starting with the second 'hit':
Yes this is possible the pendulum may have only struck the bracket six times. In that case there would only be three intervals.
The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous):
The pendulum is approximately 11.3 centimeters long.
Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging:
.313, .609, .656
Your description of the pendulum's motion from release to the 2d hit:
Between release and first hit, the pendulum swings from about a 45 degree angle with the bracket side to hit it in less than .313 seconds. This motion was to fast for me to be able to time it accurately but I know the time between the release and the second hit was .313 seconds.
Your description of the pendulum's motion from the 2d hit to 4th hit:
The pendulum hits the bracket and swings back out but not as far as when I held it at a 45 degree angle. The time is .297 seconds between the first hit and the second.
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:
My results show that the motion of the pendulum was actually faster between release and the second hit and began slowing down. So the motion between second and fourth hits was a bit slower.
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 motion of the pendulum was still slower after consecutive hits. Therefore, the motion of the pendulum was slightly slower moving between the fourth and sixth hits than between the second and fourth hits.
Your conjecture as to why a clear difference occurs in some intervals vs. others:
The first time interval would be shorter than the subsequent intervals because the pendulum has just been released and there is a significant amount of energy to make the pendulum move quickly. After each hit, some energy is released and the pendulum slows down.
What evidence is there that subsequent intervals increase, decrease or remain the same:
Intervals would increase if the rythym is slowing down. This would happen if the bracket is tilted slightly forward.
Intervals would decrease if the rythym is speeding up. This would occur when the bracket is tilted back slightly.
Intervals would be relatively steady if the bracket is on a perfectly flat surface and the string is the optimal length.
What evidence is there that the time between 'hits' is independent of the amplitude of the swing?
This experiment proves that orientation of the pendulum also affects the length of the swing interval. Even though the length of the string plays a significant role, we saw in this experiment that if the length was held constant, the time intervals between hits could speed up or slow down depending on the tilt of the the bracket which held the pendulum.
Your data look good.
After the due date we will be discussing this experiment further via an online forum.