Phy 201
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' **
My pearl was touching the bracket to begin with so when I released it and let it bounce, it became more and more frequent until it stopped. When I tilted it back, the same thing happened but at a more frequent rate.
** Your description of the rhythm of the pendulum when tilted 'forward' **
This time, with the pearl hanging away from the bracket, the rhythm seemed to remain steady with each bounce.
** Your description of the process used to keep the rhythm steady and the results you observed: **
My bracket sat level with the table to begin with, so all I needed to do for the rhythm to become steady was tilt the bracket slightly forward.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
Move the bracket 45 degrees from its original position counterclockwise. In doing, so the beats/rhythm will become closer together. For each additional 45 degree rotation (you will complete 8 45 degree rotations to end up back at the original position) up to the first 180 degrees of rotation the rhythm/beats will continues to get closer and closer until they are so close that at the 180 degree mark it is so close that it only bounces a couple of times. For the last 180 degrees of rotation (in each individual 45 degree rotation) the beats/rhythm become a little more spread out each time as compared to the previous state, however they always are getting closer together.
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
I would have to tilt the pendulum forward so that the pearl is not automatically touching the bracket at equilibrium. It needs to be at rest slightly away from the bracket.
** Your report of 8 time intervals between release and the second 'hit': **
1.695
1.859
1.862
1.913
1.811
1.923
1.865
1.824
These are the time intervals for the second hit after the pearl was released in 8 separate trials. I started the timer with the release of the pearl and stopped it on the second hit to obtain the interval.
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
1.624, 1.698, 1.612, 1.687
1.659, 1.721, 1.701, 1.691
1.599, 1.583, 1.670
1.612, 1.598, 1.626, 1.689
Each trial except for the 3rd resulted in 4 second hits. The 3rd resulted in only 3 second hits.
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
7.8 cm
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
1.623, 1.650, 1.652, 1.689
** 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
From release to the first hit you only go from equilibrium to extreme point once. When you are comparing first hit to second hit, it has to go through the extreme/equilibrium process twice.
** 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: **
There are 3 intervals between the release and the second hit and 4 between the second hit and the fourth 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: **
The intervals between both the second to fourth hits and the fourth to second hits are 4.
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
Because you only have 1 interval from release to the first hit, and from the first hit to the second hit you would have 2 intervals.
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
Stay the same, because the only time they would be less would be from release to the 1st hit. All second hit intervals should be the same.
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
Because as long as the length stays the same so will the distance from extremem point to equilibrium. Changeing the length will change the distance.
** **
2 hours
** **
Your descriptions are very good, as are your answers to the questions, and you almost certainly set the pendulum up correctly.
However 1.6-second intervals would occur with a pendulum over 2 feet long. Much shorter intervals would occur with a 7.8 cm pendulum.
I assume you used the TIMER and the intervals you reported were the intervals recorded by the TIMER.