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Rotational dynamics - System in Equilibrium

  1. Apr 20, 2012 #1
    Hi all, first year MechEng student here, final question of the final assignment of the year, would appreciate any assistance:

    1. The problem statement, all variables and given/known data
    A 0.150 kg yo-yo has an outer radius R that is 5.60 times greater than the radius r of its axle. The yo-yo is in equilibrium if a mass m is suspended from its outer edge, as shown in the figure .


    Find the tension T1

    Find the tension T2

    Find the mass 'm'

    2. Relevant equations

    3. The attempt at a solution
    Having drawn FBD's for the system, I found no problem in deriving an equation for T1 (if I find this I'm sure I will have no problem with the rest) however it contained variables which when submitted, I was told the answer was not to contain. After much struggling I can't see how it can be done.
  2. jcsd
  3. Apr 21, 2012 #2


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    welcome to pf!

    hi numan-chris! welcome to pf! :wink:

    show us your full calculations, and then we'll see what went wrong, and we'll know how to help! :smile:
  4. Apr 21, 2012 #3
    thank you for the reply, managed to solve the problem myself about 5 minutes ago, was missing a variable from one of the simultaneous equations I needed, novice mistake!
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