pearl pendulum

Your work on pearl pendulum 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:

Moving right along today.

Your description of the rhythm of the pendulum when tilted 'back'

The sounds get closer together meaning that the rhythm is getting faster. It sounds something like this: tink---tink--tink-tink,tink,tink,ta,ta,tata. Thus indicating to me that the rhythm is getting faster.

Your description of the rhythm of the pendulum when tilted 'forward'

Interesting. The rhythm appears to remain constant, it just hits with less force each time causing it to fade slighty at the end and then slowing the rhythm some.

Your description of the process used to keep the rhythm steady and the results you observed:

Could we call the process leveling? (Or as carpenters call it getting plum and square).

That would be a good term to use.

Itgot about 16 or 17 bumps each time with a constant tink-tink-tink-tink-ta-ta-ta (at the end)

Your description of what happened on the tilted surface, rotating the system 45 degrees at a time:

When I first begin the experiment. the base of the bracket is parallel with the edge of book part where it opens. The pendulum part is facing downhill. As I release the pearl in this direction I get about 15 touches with a slowing rhythm. I then turn the bracket at 45 degrees pointing toward the bottom of the spine of the textbook. I get about 17 touches but the rhythm still slows. I then turn the bracket another 45 degrees (90 from the intial placement) with the bracket facing the middle of the spine. I get about 15 touches with a steady rhythm. I turn the bracket another 45 degrees (135 from inital placement) so that the bracket/pearl is facing the top corner of the textbook at an uphill angle. I'm only getting about 12 touches here with the rhythm increasing. I will now move the bracket until it is parallel with the edge of the book facing directly uphill (A complete 180 from inital placement). I'm only getting about 10 touches with the rhythm increasing.

Your description of how you oriented the bracket on the tilted surface to obtain a steady rhythm:

You would want it to be as level as possible and as straight up and down as possible. A perfect vertical and horizontal if you will.

Your report of 8 time intervals between release and the second 'hit':

.328,.383,.281,.266,.328,.391,.273,.328,.281,.382,.265

.273,.328,.328,.335,.328,.328,.273,.328,.390,.265,.335,.328

.335,.328,.328,.328,.335,.328,.218,.382

.328,.273,.328,.281,.266,.328,.336,.328,.328,.391,.430

.325,.328,.281,.328,.273,.391,.273,.328,.328,.328

.328,.328,.328,.336,.265,.328,.335,.328,.328,.328,.390

Your report of 4 trials timing alternate hits starting with the second 'hit':

.617,.594,.719,.664,.711

.594,.664,.656,.711,.609

.539,.718,.602,.656,.719,.664

.602,.664,656,.664

The length of your pendulum in cm (you might have reported length in mm; the request in your instructions might have been ambiguous):

9.6 CM

Your time intervals for alternate 'hits', starting from release until the pendulum stops swinging:

.59,.66,.69

Your description of the pendulum's motion from release to the 2d hit:

The first hit usually goes to the center of the bracket.

Your description of the pendulum's motion from the 2d hit to 4th hit:

Depending on if the first 'hit' was good or not the pearl will either try to come to the same spot or go left or right if it hit at an angle.

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:

As long as the pendulum is hitting solid in the center it will continue to hit at an even pace.

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:

It appears that the pearl will not come as far out.

Your conjecture as to why a clear difference occurs in some intervals vs. others:

I'm not sure that I would expect that. I would expect them to be close to the same. Maybe it's faster because it is unimpeaded (sp?)as it reaches the bracket and is not counting on the force gained from the impact of the bracket and the pull of gravity (because now it's lower). Whereas gravity was working for it in the beginning it now works against it as it continues to bounce off the bracket.

What evidence is there that subsequent intervals increase, decrease or remain the same:

I expected that the rhythm would be slowed towards the end but I was wrong. It was maintained as long as the bracket was at 90 degrees.

What evidence is there that the time between 'hits' is independent of the amplitude of the swing?

I believe that this would work against that theory. Length would play a role but weight, gravity and how the pendulum is balanced would play a role as well.