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Applications of Resonance in Real Life, Example?

  1. Jul 8, 2010 #1
    I wonder how and where does resonance is applied in our real life. Any example?
  2. jcsd
  3. Jul 9, 2010 #2
    pushing someone on a swing , pedaling a bike
    Last edited: Jul 9, 2010
  4. Jul 9, 2010 #3


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    Tuning a radio to a particular frequency.
  5. Jul 9, 2010 #4
    You take out your Lexus SUV on a warm day and roll down the windows. The intollerable, low frequency blub-blub-blub hits you going over 40 mph. You roll up the windows after 2 miles and turn on the airconditioner. Automobile resonance is a problem most CAD design systems don't handle, it seems.
  6. Jul 9, 2010 #5
    When the mind oscillates at its resonance frequency between emotions (Jealousy/Desire, Anxiety/Ecstasy) it leads to unusually high amplitudes which we call falling in love.
  7. Jul 9, 2010 #6
  8. Jul 9, 2010 #7


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  9. Jul 10, 2010 #8


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    Darn you! I wanted to give the Tacoma Narrows Bridge example. In some of the clips you can see a man walking along the centerline of the bridge while it is in full oscillation. The centerline was along a nodal point allowing the man to walk along it with only a relatively minor perturbation from the bridge's oscillations.
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  10. Jul 10, 2010 #9
    I find that a reasonable description. Hard to prove, but reasonable.

    Experiments have been done, and meeting a woman on something like the Tacoma Narrows Bridge does empirically increase the perception of her beauty.
  11. Jul 10, 2010 #10


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    You don't understand what resonance is.
  12. Jul 10, 2010 #11
    The bridge example is classic.

    Another example (or anti-example) I believe is if there's an earthquake, sky scrapers may resonate and cause it to tip over. To counteract this, we place resonance buffers at the base. :)
  13. Jul 10, 2010 #12
    I certainly wouldn't have stated it as a valid example, as it's not intellectually honest as a claim, but it might be valid in some sense.
  14. Jul 10, 2010 #13


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    Well, even if we are very generous and grant that emotions behave the way he suggests, it's still not resonance.

    Consider a comparable example: weather. The daily temperature in your city definitely has its ups and downs, but it is by no means any form of resonance.

    Resonance involves a positive feedback loop of some sort. i.e.the value of the amplitude (distance from centreline) is fed back as input. The effect is cumulative. Therfe is also a negative fedeback loop (restoring force).

    This applies to bridges, SUV cavities and swings - but not emotions or weather.
  15. Jul 10, 2010 #14
    Yes, your weather example is a good way to illustrate the distinction, and why the emotion example was woefully inappropriate as a claim of what it is.

    However, if you look at the basic operation of neurons, it remains a reasonable assumption. It's even possible to graphically illustrate a form of Hebbian learning, analogous to neuronal activity, using a set of metronomes on a movable rubber base.

    In a basic description, neurons have a base frequency (centerline). When activated (distanced from the centerline) a set of other associated neurons gets activated. Much like a pair of metronomes on a movable base will sync up their periodicity. These will cascade to more neurons, which feedback to the initial neurons. Epilepsy can be viewed as a runaway feedback effect, much like the bridge.

    It's awfully presumptuous to go from this to some characterization of particular emotions. Not a technically valid claim. But neither is it entirely unreasonable.
    Last edited: Jul 10, 2010
  16. Jul 10, 2010 #15
    How could that collapes be caused by resonance??

    Wouldn't there have to be energy input at the resonant frequency of the structure... About .2hx from the look of the video. What would the source of this energy be? Only thing I can think of is an earthquake since it seems pretty implausible that wind was buffeting the structure at that exact frequency.
  17. Jul 10, 2010 #16
    Here is Steven Strogatz in a ted talk that demonstrate various related phenomena. He includes a scaled version of the bridge resonance, and the metronomes I mentioned.

    Yes, Duncanstives. There has to be an energy input to collapse the bridge. Just like you have to add a steady supply of pushes to bring a swing from a resting position to a significant swing height. In the bridge it can be supplied by wind, or even the periodic motion of people walking on it, like in the Strogatz video.

    Oops, forgot to link the video:
  18. Jul 10, 2010 #17
    An R-L-C circuit; one connecting a resistor, inductor and capacitor. It resonates between stored magnetic and electric energies. Please see, for example, http://en.wikipedia.org/wiki/RLC_circuit.
  19. Jul 10, 2010 #18
    Once I was driving through a ctiy, and I saw a banner suspended across the street between two streetlamps. The wind was blowing at a moderate speed, which caused the banner to move. Through sheer chance, the resonant frequency of the banner's up and down motion happened to be the same as that of both streetlamps. Due to this fact, the whole deal was oscillating with extremely violent intensity: the motion of the streetlamps at the top (most motion) had an amplitude of several feet! Those laps were in serious danger of breaking, and they were pretty thick aluminum poles. If they went, some serious damage would have been done.
  20. Jul 10, 2010 #19


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    The applied force was indeed wind.

    Read about the collapse itself:
    Then read about the aeroelastic effecxt that caused it:
  21. Jul 11, 2010 #20
    your stomache's natural frequency is about 1.4Hz and you get sea sick because a boat matches that frequency.
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