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Homework Help: Sound waves and vibrations

  1. Mar 17, 2008 #1
    [SOLVED] Sound waves and vibrations

    I read a post here on PF dated back in Nov 2003.
    'Security' needed some help with his Physics exam... and what a coincidence! I'm also working on that same exam now.

    PF Admin 'chroot' helped him with the questions...
    and I got confused with some of his answers. So I want to make sure now if I'm really wrong and he's right.

    I tried to ask him about this..... but he didn't want to because he said he's not a tutor.
    I also sent a private msg to Security but he hasn't responded.

    *******************

    Warren's (chroot) answer was TRUE for the statement:
    --A pendulum with a mass of 10g and a length of 20 cm swings back and forth MORE frequently than a pendulum with a mass of 20g and a length of 10cm.

    MY ANSWER... is FALSE because my textbook (which was also Security's) clearly says that "A long pendulum has a longer period that a shorter pendulum; that is, it swings back and forth more slowly--less frequently--than a short pendulum."
    This is because the period only depends on the length of the pendulum and the acceleration of gravity.

    So I would like to get a second opinion please!!!!! =)

    ******************************************

    2nd problem:

    Warren's answer was FALSE for the statement:
    --The wavelength produced by a violin string with a frequency of 196 Hz is GREATER than the wavelength produced by a piano string with a frequency of 262 Hz.

    My answer is TRUE.
    Why? ...... wave speed (e.g., 340 m/s) = wavelength * frequency
    So a high frequency would have a short wavelength so the product will = 340 m/s.

    Correct?

    *****************************************

    3rd problem:

    Warren's answer was TRUE for the statement:
    --When the crests of two waves overlap the result is DESTRUCTIVE interference

    My textbook says: "When the crest of one wave overlaps the crest of another, their individual effects add together. The result is a wave of increased amplitutude. This is called CONSTRUCTIVE interference."

    With that said, my answer is FALSE.



    PLEASE HELP ME ON THIS ONE!!!!!
    I NEED TO FINISH HIGH SCHOOL THIS YEAR AND I'M BEHIND!!!!!

    THANKS!!!!!







    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Mar 17, 2008 #2
    From what I can see, you're right on all accounts.
     
  4. Mar 17, 2008 #3
    Thanks!
     
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