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Homework Help: Rolling without slipping

  1. Nov 14, 2005 #1
    A block of a certain material begins to slide on an inclined plane when the plane is inclined to an angle of 14.57°. If a solid cyclinder is fashioned from the same material, what will be the maximum angle at which it will roll without slipping on the plane?

    I really have no idea where to start on this problem since the only given is the angle. I know that the moment of inertia of a cylinder is (1/2)MR^2 if thats needed at all. Any hints?
     
  2. jcsd
  3. Nov 14, 2005 #2

    Päällikkö

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    In what case does the cylinder slip (hint: friction)?
    Another hint: total acceleration is the same as the tangential acceleration if there's no slipping.

    (Would you happen to have the correct answer?)
     
    Last edited: Nov 14, 2005
  4. Nov 14, 2005 #3
    I'm having trouble with a similar problem.

    I tried finding the coeff of friction; got an arctan14.7 ...

    Then I set up the dynamics equations of the cylinder, taking the center of mass as the center of rotation; Wx - friction = ma

    And then I put in no slipping condition i.e a = (angular acceleration) X R.

    I substitude (angular acceleration) with the relevant expression using Newton's second law in angular form.

    I solve and then I get a very unlikely value of 89 degrees. Where am I wrong.
     
  5. Nov 14, 2005 #4

    Päällikkö

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    According to my calculations you should get a plain tan (not arctan).

    The rest sounds, if I understood everything correctly, fine.
     
  6. Nov 14, 2005 #5
    Oh right. Yea, tan 14.7 degrees. Thanks.
    okay now i get 38 degrees... dat bout right?
     
  7. Nov 14, 2005 #6
    I see how to do it now. Thank you
     
  8. Nov 15, 2005 #7

    Päällikkö

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    If you mean the problem in this thread (with the angle actually being 14.57), I get the same answer.

    No problem :smile:.
     
  9. Nov 15, 2005 #8
    romured question

    i think that it's a romured question in which the answer is 14.57 degree because friction doesnt pertain to shape of the block or how much is the surface of that
    i think the answer is that
     
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