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Homework Help: Translation and rotation

  1. May 30, 2008 #1
    Heres the diagram for the problem...

    http://img78.imageshack.us/img78/3248/35090397eg3.jpg [Broken]

    heres my work...

    http://img141.imageshack.us/img141/8352/33iw6.jpg [Broken]

    I made my conversions.... im starting by finding the speed at D.....its not zero because of the angular velocity.....but Im trying to figure how to add the two x components...

    the translational x component should be .833 ft/s......but for the rotational I need to account for omega.....
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. May 30, 2008 #2


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    What's the rotational speed? Is that the problem? It's r*omega. So that's the rotational speed. Now just split the velocity vector into xy components. This is basically an identical problem to you last post.
  4. May 30, 2008 #3
    And what is the question?
  5. May 30, 2008 #4


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    Good point. In the last post is was to compute the velocities at the various points.
  6. May 31, 2008 #5
    The problem is asking for the velocity at points D and B...as well as if the object is slipping.....Im still trying to figure out point D first
  7. May 31, 2008 #6
    ok I found D....it was just the rotational - translational ....

    I used the V=r*omega to get the rotational

    [tex] V_{d} = .999 - .833 = .166 ft/s = 2 in/s [/tex]

    but actually I think the signs should be reversed if you look at the vectors in my FBD...that makes sense because the magnitude is the same and the direction should be to the left which is negative...
    Last edited: May 31, 2008
  8. May 31, 2008 #7
    ok I found the velocity at point B as well.....im just not sure how to tell if the wheel is slipping or not...
  9. May 31, 2008 #8


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    If the velocity at D is non-zero, then it's slipping. If it's not slipping then point D is moving at the same speed as the road and has zero velocity.
  10. May 31, 2008 #9
    Thank You...thats what I thought....
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