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 of the bead hitting the bracket get closer together as the bead bounces more rapidly the closer it gets to the bracket.
** Your description of the rhythm of the pendulum when tilted 'forward' **
The rhythm gets faster as the bead gets closer to the bracket. However towards the end it becomes more steady as opposed to the bracket tilted backwards that continues the speed up towards the end and you can barely differentiate between the sounds. With the bracket tilted forware you can clearly hear all the little clicks all the way until the end.
** Your description of the process used to keep the rhythm steady and the results you observed: **
I didn't really have to do anything to make the rhythm steady. It seemed pretty steady to me to begin with. The bead hit the bracket about 15 times and after that it was hard to tell how many little bounces there were.
** Your description of what happened on the tilted surface (textbook and domino), rotating the system 45 degrees at a time: **
Pendulum facing down- The total number of beats seemed to be shorter than all the others but easier to distinguish all the way until the end.
Rotate 45 counterclockwise - The total number of beats seemed to be shorter.
Rotate 45 degrees counterclockwise - The number of beats was the shortest out of any of the rotations and then bead seemed to bounce from side to side.
Rotate 45 - The total number of beats was much longer than the previous.
Rotate 45 degrees (180 degrees from beginning) - Most number of beats, but towards the end they got so close together that you couldn't distinguish between the last beats.
The rotations on the left side were the same as each of the rotations on the right side.
** Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm: **
To get the most regular beat, I would orient the pendulum away from the top of the book so that it's pointing toward me. This position definately gave the most regular beat all the way until the end.
** Your report of 8 time intervals between release and the second 'hit': **
.449
.519
.512
.461
.469
.449
.512
.512
** Your report of 4 trials timing alternate hits starting with the second 'hit': **
.582, .523, .621, .621, .648
.512, .589, .629, .621, .664
.492, .519, .582, .648, .671
.589, .582, .629, .632, .629
** The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous): **
9.2 cm
** Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging: **
.544, .553, .615
** Your description of the pendulum's motion from release to the 2d hit: **
The bead obviously travels it's greatest distance between release and the first hit. Depending on the angle I release it, it may hit different spots on the bracket.
** Your description of the pendulum's motion from the 2d hit to 4th hit: **
Between the first hit and second, the bead goes about half the distance (maybe a little more) and can go from one side to the other depending on how I released the bead.
** 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: **
&#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 &#
&#Please respond with a copy of this question, a copy of any other part of this document you wish to include, and your response to the question. Indicate your response using the symbols *&##. As your title use the 'response title' suggested above (just copy and paste that title into the Title box of the Submit Work form); if no suggested title was given use your own title.
&#
The release and second hit seems to go faster than between the second and 4th hit. The second and 4th hits also appear to bounce back at the same distance while between release and second hit, the distance traveled is about half.
** 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: **
I don't really think the motion changes, but the distance traveled is significantly less between the 4th and 6th hit.
** Your conjecture as to why a clear difference occurs in some intervals vs. others: **
They are going to be shorter because we would expect the velocity to be higher. The way the velocity is going to be high is if the distance is longer and the time is shorter which is the way it is here.
** What evidence is there that subsequent intervals increase, decrease or remain the same: **
I think they are going to increase, but not by much, because the bead is obviously losing momentum as it continues.
** What evidence is there that the time between 'hits' is independent of the amplitude of the swing? **
I'm not really sure what this is asking because I don't understand what the length of a pendulum's swing depends on its length means. The two lengths are confusing. However, I don't think that it is completely independent of how far it actually swings. You could pull the bead all the way up to the top and get more beats out of the bead than if you started the swing down low.
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1 hour
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I couldn't find the copper wire in my lab kit so I just used a piece of thread. I'm not sure if this will be any different as far as the results.
The wire is small and easily missed; if you got a thread to work that's fine.
You have good data. Please respond according to my one note. My response to that submission will allow you to see just how good your data are.