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' **
From the time of release, the bead seems to speed up in its rythm. Then in the middle of the experiment, the bead taps are steady. As the bead slows they become slower.
** Your description of the rhythm of the pendulum when tilted 'forward' **
The beads are a steady rhythm and remain constant.
** Your description of the process used to keep the rhythm steady and the results you observed: **
I tilted the bracket forward just a little to make the rhythm steady. The ball hit the bracket 7 times in a steady rhythm.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
When the bracket is placed in the middle of the book that is resting on two dominos, the sound it constant for a moment and then slows down. When the bracket is turned to either side, the rhythm slows down. When the bracket is facing the part of the book where the dominos are the rhythm is constant.
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
When the bracket is at a greater angle, the beat becomes more regular. This occurred by placing the bracket farther up the incline of the book.
** Your report of 8 time intervals between release and the second 'hit': **
.688
.677
.610
.654
.697
.684
.699
.657
These results were obtained by clicking the timer button when the bead was released and then clicking once more when the bead had its second bounce. THis was repeated 8 times.
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
.571, .598, .571
.688, .625, .563
.674, .637, .628
.625, .664, .631
These results record from when the bead was released to when the bead hit the bracket every other time. It was recorded for four seperate trials.
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
71 mm
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
.640, .009, .033
A person couldn't click the mouse quickly enough to observed time intervals of .009 or .033 seconds. What did the TIMER output show here?
&#A full cycle of a free pendulum is from extreme point to equilibrium to opposite extreme point then back to equilibrium and finally back to (almost) the original extreme point.
The pearl pendulum is released from an 'extreme point' and strikes the bracket at its equilibrium point, so it doesn't get to the opposite extreme point.
Thus the period of the pendulum can be divided into four parts. From the steadiness of the rhythm we have good evidence that the motion between 'hits' takes the same time independent of the amplitude of the motion (the rhythm remains constant while the amplitude of the motion decreases). Theoretically each of the four parts of the cycle, as described above, takes the same time. Assuming this to be true, we can speak of the quarter-cycle from an extreme point to equilibrium or from equilibrium to an extreme point.
Through how many quarter-cycles does the pendulum move between release and the second 'hit'?
Through how many quarter-cycles does it move between the second and the fourth 'hit'?
What therefore should be the ratio of the time interval from 2d to 4th 'hit', to the interval from release to the 2d 'hit'?
How does this ratio compare with the results you just reported?
Does this constitute evidence for or against the theoretical hypothesis that the quarter-cycles all require the same time?
Suggested response title: description of motion of pearl pendulum &#
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From this point on you need to revise your responses, as indicated.
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** Your description of the pendulum's motion from release to the 2d hit: **
When the bead is released it is at the outermost point, it hits the bracket and swings back to the outermost point of release.
** Your description of the pendulum's motion from the 2d hit to 4th hit: **
Once the bead hits the bracket it swings back to the release point.
That's part of it, but that doesn't get you to the 4th 'hit'.
** 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: **
Once the bead hits the bracket it is slowing down and does not quite reach the release point as before.
** 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 second hit and the fourth hit are much closer in distance traveled and have the same rhythm. As the bead is slowing down at the sixth hit, the rhythm changes and the distance is shorter.
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
Because it has not hit the bracket yet.
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
time intervals should increase as the distance shortens.
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
The swing of a pendelum does rely on the length of the pendulum and is independent of how far it swings. The larger the pendulum the larger the swing.
** **
35 minutes
** **
Good results for the first half of the experiment. The second half will need some revision.
See my notes and please submit a revision as indicated.