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Homework Help: Spring Mass Problem

  1. Nov 16, 2009 #1
    1. The problem statement, all variables and given/known data

    Hi PF frens,
    I've got the attached picture translated into differential equation representation.
    However, not so sure how the r(t) and f multiply dee-y / dee-t comes about.
    Kindly advise?

    2. Relevant equations

    3. The attempt at a solution

    see attached jpeg.

    Attached Files:

  2. jcsd
  3. Nov 16, 2009 #2
    Hi there,

    From what I can see, the [tex]f \frac{dy}{dt}[/tex] seems to be the friction force applied on the system. I would guess r(t) the simple gravitational pull, but I might be mistaking.

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