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 sounds get closer together. The first clicks are further apart because the energy of the pearl bounces the pearl at a further distance from the bracket. As the energy of movement fades the pearl clicks the bracket more frequently because it is not traveling as far from the bracket.

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

The sounds become further apart. The first clicks are louder, then the rythm slows as it hangs out from the bracket longer with each swing, the energy to propell it toward the bracket is decreasing.

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

The rythm was only steady when the bracket was placed on a level surface. I placed a few peaces of thick paper under the bracket on my desk in order to achieve a more level surface. The pendulum hit the bracket 9 times.

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

The first placement of the bracket is parallel to the long sides of the book in such a way that the pearls are facing you. Once the pearl is pulled back and released note the beat-does it begin to get slower, faster, or is it the same. The first reading, as the pearls facing you is about the same beat.

As you rotate the bracket 45 degrees counterclockwise and do the exact same motion, the beats become closer together

Rotate another 45 degrees and the sounds are still getting closer together.

Rotate another 45 degrees and the sound gets closer.

In fact the next two rotations the sounds still appear to be gettin closer with each hit on the bracket.

It is not until the last two rotations that the sounds appear to be further apart.

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

The most regular beat of the pendelum is that start out position with the pearls oriented toward me. This is because at this position, (there is variance in the level of the book surface) the pearl is closes to merely touching the bracket.

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

.260

.270

.251

.260

.351

.281

.221

.370

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

.481,.500,.521,.651

.261,.651,.450,.521

.471,.521,.571,.610

.451,.551,.600,.611

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

78mm

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

.416,.556,.536

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

Between release and first hit the pendelum travels from a perpendicular position to roughly a parallel position upon striking the bracket. This occurs quite rapidly.

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

Between the first and second hit the pendelum does not travel as far because it has lost some of its energy to the collision with the bracket. The first motion is a product of the potential energy of the pendelum.

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 motion between the release and the second hit has a lesser time interval than does the motion between the second and 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 time between the fourth and sixth hit is less because the energy has began to decrease so much.

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

This is time when the pendelum first dropped, it makes sense that this release of potential energy causes the pearl to quickly crash into the bracket.

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

Subsequent time intervals should decrease because the pendelum does not have the energy to continue swinging to higher lengths, but if the pearl is very close to just touching the bracket they should stay the same.

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

No matter how far the pendelum actually swings the length of the swing is always correlated to the length. If the bracket is on a level surface the intervals will be even.