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Homework Help: Volume and pressure

  1. Apr 11, 2007 #1
    1. The problem statement, all variables and given/known data
    When physicians diagnose arterial blockages, they quote the reduction in flow rate. If the flow rate in an artery has been reduced to 30% of its normal value due to plaque formation, and the average pressure difference has increased by 30%, by what factor has the plaque reduced the radius of the artery?

    2. Relevant equations

    Poiseuille's Law.

    3. The attempt at a solution

    what i used was R=(.7/1.3)^.25 and get that only 85.6% of the radius of the artery is available, and has been reduced by 14.4%
  2. jcsd
  3. Apr 11, 2007 #2
    I think you want to use .3 in the numerator, ie

    flow is now 30 percent of original, not been reduced by 30%
    Last edited: Apr 11, 2007
  4. Apr 11, 2007 #3
    wouldn't the presure rate be increased by .3 so from its original, which is 1 and add .3 for the increase. But yeah i just tried .3 and it didnt work
  5. Apr 11, 2007 #4
    Its both .3 and 1.3, (.3/1.3)^.25 is that what you tried?
  6. Apr 11, 2007 #5
    yeah you are right denverdoc! thx
  7. Apr 11, 2007 #6
    NP. FYI when occlusion reaches 80 percent and above, bad news. This guy has lost some exercise tolerance but still in decent shape re meeting oxygen demands.
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