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Is damped oscillation a kind of forced oscillation?

  1. Apr 4, 2005 #1
    I am confused!!
    Forced oscillation is the one which a periodic force is imposed on a oscillating system.
    For a damped oscillator, the damping force is proportional to velocity which varies periodically. Does it mean that the damping force is a periodic force and the damped oscillation is a forced oscillation?
     
  2. jcsd
  3. Apr 4, 2005 #2

    dextercioby

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    You could say that,but the force would still be damped,even though periodic...

    Daniel.
     
  4. Apr 4, 2005 #3

    brewnog

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    No, I wouldn't say that. I'd only call an oscillation forced if something outside the system is imposing that periodic force. A dashpot is part of the system, I would not consider it an external force.
     
  5. Apr 4, 2005 #4

    dextercioby

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    Yes,i agree,terminology & conventions would reccomend otherwise,but the mathematical structure is the same...

    Daniel.
     
  6. Apr 4, 2005 #5

    HallsofIvy

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    Mathematically the differential equation mx"+ cx+ kx= f(t) gives an "oscillatory" solution as long as the discriminant c2- 4mk< 0. A "damped" oscillation is one in which c> 0. A "forced" oscillation is one in which f(t) is not identically 0.

    No, in that sense, "damped" and "forced" are completely independent.
     
  7. Apr 4, 2005 #6

    Andrew Mason

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    The period of the damping force is determined by the period of the oscillating system (ie they are equal) and the Amplitude is always decreasing (exponentially). In a forced simple harmonic oscillator, the period of the force is independent of the oscillating system and the amplitude is constant. So the damped oscillation is not a type of forced oscillation.

    AM
     
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