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Homework Help: Kinematics of a four bar linkage system

  1. Oct 16, 2016 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    I have 2 (basic) questions about this system:

    1) The question says that ωAB = ωABk, I understand that bold indicates vectors whilst the plain text indicates a magnitude so ωAB (magnitude) multiplied by k (direction vector) gives you the vector ωAB. However, why do we multiply the magnitude by k (to yield the vector ωAB) as opposed to multiplying by i or j? I'm trying to picture this in my head but struggling to.

    2) Am I correct in saying that ωAB = ωBA? That is, does the order of the letters in the subscript of the vector matter? Does this matter for magnitudes (e.g. ωAB = ωBA), vectors^ or both/neither?
  2. jcsd
  3. Oct 20, 2016 #2


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    This isn't my subject really so I'm not the best person to reply but since you haven't had one...

    I believe this is just another way to represent rotation called the Axis–angle representation.


    and it's scalar multiplication not ordinary or vector multiplication..

    Last edited: Oct 20, 2016
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