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  1. #1
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    Post word problem

    The period of a simple pendulum is directly proportional to the square root of its length. If a pendulum has a length of 6 feet and a period of 2 seconds, to what lemgth should it be shortened to achieve a 1 second period? My answer is 3 feet but I'm not sure. Thanks for checking this problem.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by kwtolley
    The period of a simple pendulum is directly proportional to the square root of its length. If a pendulum has a length of 6 feet and a period of 2 seconds, to what lemgth should it be shortened to achieve a 1 second period? My answer is 3 feet but I'm not sure. Thanks for checking this problem.
    What we are told may be rewritten as:

    period(length)=k\sqrt{length}

    also:

    period(6)=k\sqrt{6}=2

    so: k=2/ \sqrt{6}

    Now if the period is 1 s:

    period(length)=2/ \sqrt{6}\times \sqrt{length}=1

    rewriting this gives:

    length=3/2\ ft

    RonL
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  3. #3
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    Question answer

    Ok I see your answer but I have to chose 1 foot, 1.5 feet, 2 feet, or 3 feet. I guess it is 1.5 feet. thanks for all the help given.
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by kwtolley
    Ok I see your answer but I have to chose 1 foot, 1.5 feet, 2 feet, or 3 feet. I guess it is 1.5 feet. thanks for all the help given.
    I think you will find that 3/2=1.5 ft, so yes.

    RonL
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  5. #5
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    Smile answer

    Thanks thats what I thought too.
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