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' **
The sounds get closer together, I tried the experiment several times and the spaces between each bounce get less and less until the sound disappears.
** Your description of the rhythm of the pendulum when tilted 'forward' **
The sounds once again get closer together. The rhythm of the sound speed up until it is gone.
** Your description of the process used to keep the rhythm steady and the results you observed: **
In order to make the rhythm of the ball remain constant we have to leave the tilt the bracket forward enough to make the ball hangs perpendicular to the ground away from the bracket.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
For this experiment you will need to place one domino under each corners of your book. Line the tall end of your bracket toward the books spine. Conduct the experiment four times, one facing each direction on a flat service. This will yield the results that the rhythm of the ball continues to get closer together until the ball stops moving. We can place dominos under the corners until the string hangs perpendicular to the level table and this causes the rhythm of the ball to remain constant.
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
We can place dominos under the corners until the string hangs perpendicular to the level table and this causes the rhythm of the ball to remain constant.
** Your report of 8 time intervals between release and the second 'hit': **
.188
.188
.192
.185
.188
.187
.190
.188
The numbers above are the time intervals obtained from first clicking the timer when the ball is released and then we click the timer again the first time the ball hits the bracket.
You did a pretty good job of timing that very short interval, but the interval requested here was from release to the second 'hit'. No a to redo anything, but keep this in mind when reading the remaining comments.
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
.301, 1.20, 1.25, 1.23, 1.29,
.318, 1.27, 1.28, 1.31,
.325, 1.28, 1.27, 1.28, 1.31
.295. 1.26, 1.28, 1.24, 1.25, 1.30
.325, 1.27, 1.26, 1.30,
.293, 1.26, 1.28, 1.29, 1.33
.299, 1.27, 1.26, 1.29
.319, 1.27, 1.23, 1.26, 1.29
I recorded the data in intervals of two bounces. It seems that at the last bounce always had a greater interval than the previous bounces.
You appear to be reporting and interval off about .3 seconds followed by intervals around 1.2 seconds. The pendulum is much more consistent than that, and a pendulum 9.3 cm long will not require 1.2 seconds between strikes with the bracket. 1.2 seconds is close to the interval that would correspond to 2 complete cycles of the pendulum; however this doesn't explain the short time intervals at the beginning of each line.
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
9.3cm
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
.25, 1.27, 1.28
** Your description of the pendulum's motion from release to the 2d hit: **
The first cycle of the pendulum does not make it to its extreme point before it makes contact with the bracket.
** Your description of the pendulum's motion from the 2d hit to 4th hit: **
The contact with the bracket on the first cycle slows it down enough so that on the second cycle the pendulum equals out and reaches its extreme point on the second cycle.
If the pendulum is set up in such a way as to achieve a constant rhythm, it will encounter the bracket every time it reaches the equilibrium point and will bounce back and forth between the equilibrium point and the extreme position, always on the same side of the equilibrium point. It will never reach the opposite equilibrium point.
** 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: **
The release to second hit takes less time that the motion from the second to forth hit does.
** 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 motion does not differ very much at all
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
Because it is just half a cycle
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
Increase
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
According to the results in order to make the pendulum swing and continue the cycle the length of it is not as important as where the pear hangs at the initial point of the experiment.
** **
2 and a half hours
** **
I'm not sure you observed the system as instructed. If that is the case, don't repeat the entire experiment, but take a couple of timings and clarify what was done.
&#Please see my notes and submit a copy of this document with revisions and/or questions, and mark your insertions with &&&&. &#