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:

I am not too sure if my timing was right on this.

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

The rhythm starts out faster and gets progressively slower with each beat. The sounds start out louder and get softer with each beat.

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

With each bounce, there is more frequency when the bracket ws tilted forward. The sound is a little higher pitched and louder. The sound get closer together when the pearl is about to stop bouncing. Thus the rhythm gets faster.

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

I had to tilt the bracket slightly forward. When I did this, I could hear about 5 moderately constant beats.

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

When the bracket was facing the direction the dominos were placed, the sound was close together. When the bracket was turned to the left 45 degrees, the sound not as close together as the first. The sound was still close together, just not as much compared to the first. When the bracket was turned another 45 degrees, the sound was further apart than the first two sounds. At this position, the bracket was facing the left hand side of the book. When the bracket was turned another 45 degrees to the left, the sound was still further apart. When the bracket was turned another 45 degress, it was facing the downward to the opposite side of the book. This produced a sound the most further apart. The bracket was turned another 45 degrees, producing a sound slightly closer together. When the bracket was turned another 45 degrees to the left, the sound became closer together. Yet the bracket was turned another 45 degrees to produce a sound closer and closer together to the original position.

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

I would probably take out the dominos under the book so the pendulum is even.

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

Trial 1:

2 5648.297 .390625

3 5648.563 .265625

4 5648.844 .28125

5 5649.109 .265625

6 5649.375 .265625

7 5649.656 .28125

8 5649.953 .296875

Trial 2: 1 5754.953 5754.953

2 5755.328 .375

3 5755.578 .25

4 5755.875 .296875

5 5756.141 .265625

6 5756.438 .296875

7 5756.734 .296875

8 5757.031 .296875

Trial 3:

1 5789.938 5789.938

2 5790.297 .359375

3 5790.672 .375

4 5790.922 .25

5 5791.203 .28125

6 5791.469 .265625

7 5791.766 .296875

8 5792 .234375

9 5792.25 .25

Trial 4:

1 5831.484 5831.484

2 5831.75 .265625

3 5832 .25

4 5832.25 .25

5 5832.516 .265625

6 5832.781 .265625

7 5833.031 .25

8 5833.297 .265625

9 5833.563 .265625

Trial 5:

1 5878.688 5878.688

2 5879.141 .453125

3 5879.375 .234375

4 5879.688 .3125

5 5879.938 .25

6 5880.234 .296875

7 5880.484 .25

8 5880.766 .28125

9 5881.031 .265625

Trial 6:

1 5956.984 5956.984

2 5957.219 .234375

3 5957.516 .296875

4 5957.813 .296875

5 5958.109 .296875

6 5958.391 .28125

7 5958.672 .28125

8 5958.969 .296875

9 5959.203 .234375

Trial 7:

1 5982.313 5982.313

2 5982.594 .28125

3 5982.906 .3125

4 5983.172 .265625

5 5983.453 .28125

6 5983.703 .25

7 5984 .296875

8 5984.281 .28125

9 5984.547 .265625

Trial 8:

1 6032.328 6032.328

2 6032.938 .609375

3 6033.203 .265625

4 6033.453 .25

5 6033.719 .265625

6 6033.953 .234375

7 6034.219 .265625

8 6034.484 .265625

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

Trial 1: .391, .625, .703

Trial 2: .453, .688, .672

Trial 3: .594, .626, .705

Trial 4: .609, .621, .594

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

107 mm

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

.51, .13, .05

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

The pendulum is being pulled back and released to one spot. The pendulum hits that one particular spot at a fast hit.

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

The pedulum hit once and goes backward. However it does not go as far back as the previous release. It does not hit the exact same spot as the first hit during the second hit.

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 pendulum gets closer and closer to the bracket between the second hit and fourth hit. With the release and the second hit, the string and the pearl were farther away from the bracket.

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 of the swinging pendulum keeps getting shorter and shorter with each progressive hit. Therefore the motion between the fourth and the sixth hit is much shorter than the second and the fourth.

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

Because in the first time interval, there is the most energy being released. With more energy from the pull back, the pendulum hits the bracket faster.

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

We would expect the time intervals to get slower because energy is being used after each hit.

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

I think this experiment does not provide information about how far back to pull back on the pendulum. I think the experiment supported the hypothesis that the longer the string the longer the time interval. This was shown through the experiment because in the beginning, the shorter string hit the bracket faster than the longer string we used later in the experiment. I think this is because less energy was being used by the pendulum with the shorter string. More energy was therefore used the pendulum with the longer string.

You have good data and your answers are well stated.

Once all experiments have been received, we will be discussing this experiment further via an online forum.