Pendulum 8-22

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course phy 201

8/28 1030

Remember that the frequency of a pendulum is how many oscillations it completes in a unit of time. For the exercise in today's class, we measure frequencies in cycles per minute.

Using your data sheet from today's class, answer the following:

What were the lengths of your two pendulums?

**** 20 3/16 inch and 10 1/4 inch

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What were the frequencies of your pendulums?

**** 41 and 56

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What was the ratio of the length of the longer to the length of the shorter?

****

1.366

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What was the ratio of the frequency of the shorter to the frequency of the longer?

****

.508

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The ratio of 41 to 56 isn't .508. The square of that ratio might well be .508, so I suspect you might have gotten carried away and squared the thing.

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What is the square of the ratio of lengths, and what is the square root of the ratio of the lengths?

**** square 1.865 square root 1.168

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What is the square of the ratio of the frequencies, and what is the square root of the ratio of the frequencies?

**** square .258 square root .7127

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Find two pendulum lengths such that the frequency of one pendulum is half that of the other.

What were your lengths?

**** 20 3/16 inch and 4 15/16 inch

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What is the ratio of your lengths?

**** .245 and 4.085

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How did you arrive at your two lengths?

****

I counted the times that the pendulum completed one oscillated in one minute. I did this three times and figured an average. I then tested different lenghts of string until I found a spot where the pendulum oscillated doubled the first count.

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You've got good data, and good results. But do see my one note.

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