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To estimate the required torque

  1. Jun 19, 2009 #1
    a mass of 100N has to be lifted up via string attached to pulley.
    What is the torque required to rotate that pulley
     
  2. jcsd
  3. Jun 19, 2009 #2

    tiny-tim

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    Welcome to PF!

    Hi ravipatil666! Welcome to PF! :smile:

    Torque = distance "cross" force …

    so what is the radius of the pulley? :wink:
     
  4. Jun 19, 2009 #3
    the pulley has 26mm radius..
    f=m*g
    r=.026
    and T=f*r (N-m)
    thats it?
     
  5. Jun 19, 2009 #4
    and thanks 4 my post tiny-tim
     
  6. Jun 19, 2009 #5

    tiny-tim

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    Yup! It's as easy as that! :biggrin:

    (except that you don't need the "g", since the mass is given to you in newtons, not kg, anyway :wink: )
     
  7. Jun 19, 2009 #6
    oh ya my mistake....
     
  8. Jun 19, 2009 #7
    and i want to know when does the eq T=I*alpha
    comes into picture???
     
  9. Jun 19, 2009 #8
    and also 1 more question
    wht happens if the width of the pulley s increased?
    bcoz width has nothing to do in the eq only radius s considered.
     
  10. Jun 19, 2009 #9

    tiny-tim

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    (have an alpha: α :wink:)

    ah, that's only if the pulley has non-negligible mass, and you want to find how fast it's rotating …

    I is the moment of inertia of the pulley, and α is the angular acceleration. :wink:
    nothing … only the radius matters. :smile:
     
  11. Jun 19, 2009 #10
    Increasing the width of the pulley will require more material which will increase the value of I, so the change will show up there, even though the width does not appear directly in any of the equations you have written.
     
  12. Jun 22, 2009 #11
    thanks(dhanyawaad).........
     
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