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:

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

The rhythm gets faster (sounds get closer together).

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

Rhythm gets slower (sounds get further apart).

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

I placed two sheets of paper under the back end of the pendulum to tilt it forward just slightly. The rhythm sounded very steady, and I heard the pearl hit 15 times.

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

bracket orientation: facing right side, sounds get closer.

bracket orientation: facing bottom end of book, sounds get further apart.

bracket orientation: facing left side of book, sounds get closer.

bracket orientation: facing top end of book, sounds get closer.

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

To get a more regular beat, I would orient the bracket to face the lower left and right corners of the book.

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

.414, .406, .313, .398, .391, .461, .461, .477, .461, .477

.328, .289, .391, .430, .484, .484, .453, .5, .539, .531, .531, .516

.359, .273, .367, .352, .336, .297, .383, .406, .375, .422, .531

.375, .461, .359,.298, .313, .344, .344, .344, .320, .359, .406

.296, .391, .039, .531, .461, .430, .398, .320, .359, .398, .507

.305, .383, .359, .461, .391, .438, .5, .484, .531

.477, .039, .461, .359, .515, .047, .531, .351, .438, .492

.445, .039, .430, .305, .389, .328, .320, .381, .398, .359, .414, .461

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

.664, .672, .734, 1.03, .984, .961, .898, .859

.593, .938, .805, .704, .758, .969, .773, .719

.516, .695, .75, .711, .742, .758, .734, .625, .844

.617, .695, .797, .992, 1.13, 1.07, .805

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

71 mm

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

.60, .75, .77

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

The pendulum swings to the center, sometimes very slightly to the left on the first hit.

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

the pendulum swings left and right between hits.

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:

When the pendulum hits the center on the first hit, it is traveling less distance than when it swings back and forth between the hits.

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 starts to come back to the center.

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

Time interval should be shorter due to the less distance traveled.

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

I would expect subsequent intervals to start to stay the same.

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

This experiment would negate the hypothesis that the length of the pendulum's swing depends only on its length. It does in fact depend on how far it swings.