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Tension between two cables, not sure what to do.

  1. Oct 9, 2011 #1
    1. The problem statement, all variables and given/known data
    In treating spinal injuries, it is often necessary to provide some tension along the spinal column to stretch the backbone. One device for doing this is the Stryker frame, illustrated in part (a) of the figure. A weight is attached to the patient (sometimes around a neck collar, as shown in part (b) of the figure), and friction between the person's body and the bed prevents sliding.

    PART A: If the coefficient of static friction between a 96.5kg patient's body and the bed is 0.725, what is the maximum traction force along the spinal column that can provide without causing the patient to slide?

    PART B: Under the conditions of maximum traction, what is the tension in each cable attached to the neck collar? [Picture is attached]

    2. Relevant equations
    Newtons first law ƩF=0 in equilibrium.

    3. The attempt at a solution

    This is for Mastering Physics btw.

    I was able to find Part A: with T=Fs=μmg=(.725)(96.5)(9.8)=686N

    But I am having trouble with part B. I see that the angles are equal so I assume that they are sharing equal tension. I broke them down by x and y components and found the magnitude but that was incorrect, I also used just the y component and that was incorrect as well. If someone could point me in the right direction that would help so much!

    Attached Files:

  2. jcsd
  3. Oct 10, 2011 #2


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    Gold Member

    Does this look right?

    Attached Files:

  4. Oct 10, 2011 #3
    Definitely! Thanks, I definitely have to start focusing more on the free body diagrams.
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