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 rhythm gets faster as the pearl bounces against the bracket.
** Your description of the rhythm of the pendulum when tilted 'forward' **
The rhythm gets slower when the bracket if tilted forward.
** Your description of the process used to keep the rhythm steady and the results you observed: **
I placed some paper under the front of the bracket to make the rhythm as steady as possible, the pendulum hit the bracket 5 times.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
Pendulum Face Rhythm
Up ramp Fastest
45 deg turn Slower
45 deg turn Slower
45 deg turn Slower
45 deg turn Slower
Down ramp Slowest
45 deg turn Faster
45 deg turn Faster
45 deg turn Faster
45 deg turn Faster
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
Orient the bracket facing right or left side of ramp.
** Your report of 8 time intervals between release and the second 'hit': **
.484
.469
.391
.359
.328
.328
.313
.297
These are the times between release of the pendulum and the time it takes to strike the bracket the second time.
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
.313, .328, .219
.266, .328, .297
.328, .297, .25
.313, .328, .266, .25
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
52 mm
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
.313
.289
** Your description of the pendulum's motion from release to the 2d hit: **
The first motion is not as smooth as the motions after the first hit.
** Your description of the pendulum's motion from the 2d hit to 4th hit: **
This is a shorter, smoother motion than after release.
** 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: **
It is a longer motion.
&#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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** 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: **
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
Because the pendulum is moving faster in the first time interval.
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
Decrease, because the pendulum is not moving as far in subsequent time intervals.
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
The length of the pendulum's swing is also dependent on the angle of the bracket, because it affected the time interval when the angle was changed.
** **
about 45 mins
** **
Please respond as indicated above so your data can be compared to your responses