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Where would an ideal wire break?

  1. Feb 7, 2009 #1
    Here's a no brainer for you guys...

    Suppose we have an ideal straight wire lying on the table. Then we pull it with equal forces on both sides. Let's say we start from zero force and then gradually magnify the force. A one point, the wire would break. But, where would it break? As the situation is totally symmetrical, there is no preffered point on it. Would it break into infinitely many pieces? Would it not break at all? In the center?

    Thanks...
     
  2. jcsd
  3. Feb 7, 2009 #2
    Considering the wire is homogeneous (i.e hypothetical wire) and 100% brittle; when the force increments, there's actually a shockwave traveling along the length of the wire, now since the shockwave will originate at the ends, i.e the ends will the first to experience the ultimate stress limit, it will break from the ends from where force is applied.
     
  4. Feb 7, 2009 #3
    Hm, interesting, I'd never thought of that!
     
  5. Feb 7, 2009 #4
    I understand we're talking about an "ideal" wire here, but "ideal" wires don't actually exist in the real world, so the question is more an exercise in futility.

    In the real world, nothing is manufactured to absolute perfection therefore, nothing possesses 100% uniformity in its manufacture or material consistency. This makes it just as likely for the wire to separate anywhere between the two points that are producing the stress. It simply depends upon which point is the weakest, which brings to mind the old adage; "A chain is only as strong as its weakest link". Naturally, this applies to a wire as well.
     
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