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Homework Help: Shm (2)

  1. Feb 22, 2004 #1
    2 pendulum bobs X and Y have the same length and sixe.
    ( pendulum bob X is made from copper while Y -> polystyrene )
    there is another pendulum Z with variable length ( Z -> lead )

    when pendulum Z is set oscillating with frequency f each time at different length, pendulum X and Y will be forced into oscillation. sketch the graph to show the variation of amplitude for pendulum X and Y with frequency, f.

    i know that is should be the pendulum X which has a higher peak in the graph compared to pendulum Y. but, how should i explain it using physics.

    since T=2pi sqrt(l/g), mass seems to be independent of the frequency.
  2. jcsd
  3. Feb 23, 2004 #2

    Tom Mattson

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    I'm not sure I understand. Are these oscillators X and Y coupled via oscillator Z? Or are they just 3 independent oscillators?
  4. Feb 24, 2004 #3
    something like this

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  5. Feb 24, 2004 #4


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    That still doesn't tell us anything. A pendulum can move with any motion at its pivot. How does Z "force" X and Y into oscillation? In any case, why do you think X would have a "higher peak" than Y? The only difference between them is the material they are made of which will change their mass and weight but neither of those is relevant to period.
  6. Feb 27, 2004 #5
    actually, it happens just like the experiment to show the effect of resonance, where pendulum Z act as driver pendulum, which is forced to oscillate as Z is being oscillate.
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