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Tension in the rotating chain

  1. Jun 10, 2014 #1
    1. The problem statement, all variables and given/known data

    A metallic chain with a length ‘l’ andd whose ends are joined together is fitted onto a wooden disc as shown in the figure.The disc rotates with a speed of n revolutions per second.Find the tension of the chain T if its mass is m.

    2. Relevant equations

    3. The attempt at a solution

    Honestly I have very little idea about how to approach this problem .

    All I know is that every part of the chain is undergoing centripetal acceleration as the chain is rotating .Since the speed is constant there would be no tangential acceleration.

    ω = 2nπ

    Please help me with this problem .

    Thanks .

    Attached Files:

  2. jcsd
  3. Jun 11, 2014 #2


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    Well, centripetal acceleration requires a centripetal force. What can possibly be the source of that force ?
    Think of a ring of people holding hands and dancing around with considerable speed. What if a hand lets go ?
  4. Jun 11, 2014 #3
    Component of tension in the radial direction. But how do I find that component ?

    The ring will fall apart .
  5. Jun 11, 2014 #4


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    To find that radial component, draw a section of the chain and note that the vector sum of the tensions points just where you want it !
  6. Jun 17, 2014 #5
    Sorry for the late response .

    I still don't understand how to approach this problem.
  7. Jun 17, 2014 #6
    Doesn't the wooden disc play any role in providing centripetal force to the chain ?
  8. Jun 17, 2014 #7


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    Not really. How could it? All it can do is push radially outward (a normal force!), which doesn't help: it is in an altogether wrong direction ! Iron doesn't have a tendency to stick to wood by some physical force...

    Did you draw a section of the chain and discover how the sum of the tensions working on it points in a desirable direction ?
    Last edited: Jun 17, 2014
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