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Homework Help: Circular Motion and acceleration

  1. Jul 22, 2007 #1
    Ok, for the circular motion, where we are suppose to have 0 acceleration,
    this is the problem i have

    My question ask for mass of the washers and paper clips by equating Fc to Fg,

    and I am given the # of washers,
    The radius
    and the mass of the stopper.

    and the period

    now it ask me for mass

    how do i find this?
    i kno that
    Fc = mv^2/r
    Fc = 4pi^2rm/T^2
    Fg = mg,
    but how do i do it?
    i can't seem to figure it out,
    even after i figure out the speed, it doesn't help, i have 2 unknowns...The
    Fc, and the mass...
    help please?

    Incase this helps, i am swinging the tubber sopper, with a tube, and below the tube is the paper clip to keep my distance so i kno i am swinging at a constant speed, then at the end of string is my washers for the mass.
    Last edited: Jul 22, 2007
  2. jcsd
  3. Jul 22, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    The centripetal acceleration is certainly not zero!


    So you are given the mass of the stopper and you must compute the mass of the washers?

    What mass does m stand for here?
    What mass does m stand for here?

    Realize that those equations use different masses: one uses the known mass of the stopper; the other uses the unknown mass of the washers.
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