Phy 121
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.
** Your description of the rhythm of the pendulum when tilted 'forward' **
The rhythm slows.
** Your description of the process used to keep the rhythm steady and the results you observed: **
I placed a stack of printer paper under the opposing end of the bracket and removed a few at a time until the bead was barely touching the bracket. The rhythm seemed very steady while the pendulum hit 8 times.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
I placed the bracket with the bead closest to the end of the textbook with dominoes under it. The sounds got closer together at this orientation.
Each time I rotated the base of the bracket 45 degrees counterclockwise. With the bead nearest the top left corner of the textbook the sounds still got closer.
With the bead nearest the left side of the book the sounds were almost steady.
With the bead nearest the lower left corner, the sounds got further apart.
With the bead nearest the bottom of the book and the sounds got further apart.
With the bead nearest the lower, right corner of the book, the sounds got further apart.
With the bead nearest the right side of the book, the sounds were almost steady.
With the bead nearest the top, right corner of the book, the sounds got closer together.
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
To get the most regular beat of the pendulum, the bracket needs to be oriented so the bead barely touches the bracket at rest.
** Your report of 8 time intervals between release and the second 'hit': **
.390
.375
.390
.374
.406
.375
.390
.390
I clicked the timer when the pendulum was released and again when it struck the bracket the second time. The time intervals above represent the time it took for the pendulum to strike the bracket, go back to the original position and strike the bracket again.
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
.436, .531, .545
.390, .406, .410
.515, .624, .619
.561, .609, .620
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
87 mm
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
.48, .54, .55
** Your description of the pendulum's motion from release to the 2d hit: **
1
** Your description of the pendulum's motion from the 2d hit to 4th hit: **
2
Between release and first hit, the pendulum only has to travel from extreme point to equilibrium, where it provides the first 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: **
3
From release to second hit, the pendulum's release and hit point were not at the same location but between the second and fourth hits, it starts and ends at the same location so it has to travel 1 interval further.
** 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: **
4
Between the second and fourth and between the fourth and sixth hits, the pendulum has to travel the same number of intervals, 4. With both of these, the pendulum is beginning and ending at the same location with one hit in between.
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
The first time interval only include 3 segments whereas the others include 4.
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
They should stay the same since the measurement would be from equilibrium to extreme point, back to equilibrium, extreme point and back to a hit that we timed.
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
In this experiment the pendulum wasn't actually allow to complete the full swing but still continued to stay in motion and swing.
** **
1.5
** **
&#Very good work. Let me know if you have questions. &#