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Homework Help: Challenging problem

  1. Nov 3, 2008 #1
    1. The problem statement, all variables and given/known data
    n my homework we are asked to find the magnitude of the reaction force at the pivot at a instant and earlier in the problem we found the magnitude of the angular speed at one instant, the magnitude of the angular acceleration at the same instant, and the magnitude of the acceleration of its center of mass at the same instant

    PROBLEM # 13

    2. Relevant equations
    I am lost now.... am attaching the picture

    3. The attempt at a solution
    F= (4.5)(16.43509961) (my numbers)
    but the answer is wrong..

    than I tried
    F= ma
    F= (4.5)(7.350000002) (transitional acceleration only)
    answer is still wrong :(

    my numbers =

    angular acceleration= 2.133526851
    angular velocity= 2.065684802
    Net acceleration= 16.43509961

    mass- 4.5
    rod- 6.89

    What am I doing wrong?

    Attached Files:

    Last edited: Nov 3, 2008
  2. jcsd
  3. Nov 3, 2008 #2
  4. Nov 4, 2008 #3
    so so for future users this is how you get the answer:

    than take square root of that

    but I still don't know why you get it that way.... its too late for me to plug it in to the system so I am not sure if its even right but thats how you get it....
  5. Nov 4, 2008 #4

    Doc Al

    User Avatar

    Staff: Mentor


    On the right track here. Note that F is the net force. You need to find the force of the pivot on the rod.
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