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Homework Help: Tension force question

  1. Oct 22, 2004 #1
    "A rope is strong enough to withstand a 750 N force without breaking. If two people pull on opposite ends of the rope, each with a force of 500 N, will it break? Explain."

    Am I correct in assuming that the tension force will be 500N?
    Last edited: Oct 22, 2004
  2. jcsd
  3. Oct 22, 2004 #2
    No, the total force would be 1000N since you have one force pulling on the left, and one force pulling on the right, EACH with 500N. The rope would break.
  4. Oct 22, 2004 #3
    How does one explain that however, since the net force is still 0 N ?
  5. Oct 23, 2004 #4
    Net force is zero, since
    force from the left = -500N
    force from the right = 500N

    =-500N+500N =0 N

    All this is telling you is that there is constant velocity and zero acceleration.

    However, total force of the two forces is 1000N, since it is the combined force.
  6. Nov 4, 2004 #5
    I completely forgot about this thread. Sorry for the delay and seeming lack of gratitude on my part:p

    Thanks Urban, your response helped, but I'm confused as to why, if you isolate one mass and show the forces like so, Fa - Ft = ma, the tension force will turn out to be 500N? Fa = 500N, the applied force by one team, and ma will be 0, since acceleration is zero. Therefore, the tension force would seem to be the same as the applied force?...
  7. Nov 6, 2004 #6
    imo tension force would be same as the applied force....

    From what i've learned Fapp-Ff= ma ( where ff= frictional force )

    Hence Fapp = Ff

    Imagine such a diagram where the arrows show the direction in which the people are pulling.... they do not coincied with other

    i would use Fapp-Ff=fnet if it were like this... eg. if someone is pulling a box and theere is frictional force against it... the (.) is the point of origin


    dunno if my explanation sounded stupid.. hopefully it helped.. LOL... Btw you using the Glencoe Physics text book coz i've seen the problem in mine..
  8. Nov 7, 2004 #7


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    If you think about the problem from an equilibrium point of view it is a typical mechanics of material exercise ... the "net force" == 0 applies to the system, but at a section of the rope stresses equal to 500 N / Area arise. So I'd take this as a static strength of materials problem rather than a dynamics problem.
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