Phy201
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 and the impact gets softer.
** Your description of the rhythm of the pendulum when tilted 'forward' **
The sounds get further apart and the impact gets softer.
** Your description of the process used to keep the rhythm steady and the results you observed: **
I placed a washer underneath to shim the bracket and make it level. The rhythm was steady and the pearl hit the bracket about 8 times.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
When the bracket was placed on top of the textbook with the cover facing up and a domino underneath the top left corner and another domino placed underneath the top right corner with the back side of the bracket facing the right side of the book the sounds got further apart. THe bracket was turned 45 degrees so that the back side of it now faced the top of the book and the process of pulling back then releasing the pendulum was repeated the sounds got further apart. The bracket was turned another 45 degrees so that the back side of it now faced the left side of the book the sounds remained further apart. Finally the bracket was turned another 45 degrees so that the back side of it faced the bottom of the book and the sounds got closer together.
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
By turning the bracket so that the back side of it faced the bottom left corner of the book and the front of it was half way between the top of the book and the right side of the book ( faces the top right corner)I was able to obtain the most regular beat pattern of the pendulum.
** Your report of 8 time intervals between release and the second 'hit': **
.668
.762
.625
.648
.605
.707
.645
.605
The above results are the number of seconds it took from the time the pendulum was released until the time it took for the pendulum to hit the bracket for the second time for each of the 8 trials. They were obtained by subtracting the beginning time from the end time using the timer program.
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
.789, 1.016, 1.730
.684, 1.020, 1.945
.734, 1.098, 1.547, 1.684
.617, 1.289, 1.754
The above results are the number of seconds it took from the time the pendulum was released until the time it took for the pendulum to hit the bracket for each second time ( ie. 2nd hit, 4th hit, 6th...)for each of the 4 trials. They were obtained by subtracting the beginning time from the end time using the timer program.
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
20.22
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
.706,1.106,1.744
** 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
The pearl travels 1 interval from equilibrium (first hit) to the extreme point then interval 2 is from the extreme point to equilibrium (second 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 the second hit, the pearl travels 1 interval from extreme(release) to equilibrium ( first hit), another interval from equilibrium (first hit) to the extreme point then interval 3 is from the extreme point to equilibrium (second hit). The motion between second hit and fourth hit would have 4 intervals because it starts at equilibrium (2nd hit)to extreme, extreme to equilibrium (3rd hit), equilibrium (3rd hit)to extreme, and extreme to equilibrium (4th hit).
** 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
The motion between second hit and fourth hit would have 4 intervals because it starts at equilibrium (2nd hit)to extreme, extreme to equilibrium (3rd hit), equilibrium (3rd hit)to extreme, and extreme to equilibrium (4th hit). This motion would be the same for the motion between the fourth hit and the sixth hit as it would also have 4 intervals.
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
The pendulum travels less intervals so the time is shorter. For every susequent timed hit the time increases because it is traveling through more intervals.
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
decrease
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
The pendulum can only swing to an extreme that is equal to its length,it can however swing at lengths less than that length. However the time for travel is based on the number of intervals traveled and the length of those intervals.
** **
2 hours
** **
&#Very good work. Let me know if you have questions. &#