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Homework Help: Uniform circular motion merry-go-round

  1. Sep 14, 2010 #1
    1. The problem statement, all variables and given/known data
    A purse at radius 1.90 m and a wallet at radius 2.60 m travel in uniform circular motion on the floor of a merry-go-round as the ride turns. They are on the same radial line. At one instant, the acceleration of the purse is (1.70 m/s2) + (4.60 m/s2). At that instant and in unit-vector notation, what is the acceleration of the wallet?

    2. Relevant equations
    Tan(theta)= -(V^2/r)sin(theta)/-(V^2/r)Cos(theta)
    A=V^2/r
    T(period)=2pir/v

    3. The attempt at a solution

    I used the original components of the purse to determine the angle created from the acceleration components
    1) Tan(theta)= (4.6m/s^2)/(1.70m/s^2)
    Arc Tangent (4.6/1.7)=theta and I found theta=69.72 degrees

    next, I used the angle to determine the new components of the wallet using the same velocity but at a different radius (2.6m)

    2) 2.6 Cos69.72= acceleration of wallet about x = .901m/s^2
    2.6 sin69.72 = acceleration of wallet about y = 2.44m/s^2

    -I put those components into the unite vector notation and got the problem wrong... I'm wondering why, if anyone could please help. thanks
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 14, 2010 #2

    kuruman

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    Are there unit vectors multiplying these components? If so, what are they?
     
  4. Sep 15, 2010 #3
    the only unit vectors that had been provided were the acceleration of the purse is (1.70 m/s2)i + (4.60 m/s2)j *apparently those letters didn't show up in the earlier post.
     
  5. Sep 15, 2010 #4

    kuruman

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    Can you find the magnitude of the acceleration of the purse?
    Once you have that, can you find the magnitude of the acceleration of the wallet?
    Once you have that, can you find the components of the acceleration of the wallet?

    Hint: The wallet's acceleration vector is proportional to the purse's acceleration vector. What is the constant of proportionality?
     
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