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TBR Fluids and Fluid Dynamics


Full Member
Jul 5, 2016
  1. Pre-Medical
    My question is more about unit conversion...

    Atherosclerosis is the thickening and hardening of the arterial walls. The aorta of a healthy adult has a radius of about 1.3 cm and a blood flow velocity of about 0.5 m/s. An atherosclerosis-stricken bacon epicure (lol) is found to have an effective aortic radius that is 75% of that in a healthy aorta. What is the blood flow velocity through the narrowed section of artery? (Assume that the blood's volumetric flow rate is constant for all adults.)

    V1A1 = V2A2 => V2 = (A1/A2)V1 = (pir12/pir22)V1 = (r12/(3/4r12))V1 = (1/(3/4)2)V1 = (16/9)(0.5 m/s)

    A: 0.89 m/s

    Maybe I've just been studying too long, but I don't understand why there was no conversion between m/s and cm/s?

    Last edited:


    Full Member
    5+ Year Member
    Nov 1, 2015
    1. Medical Student
      The actual radius of the aorta never actually enters into the equation because the fact that you know that it's reduced to 75% that of a normal one is enough. We're working with ratios here. Even if you had plugged it in, you could have found that the units actually cancel and that it doesn't matter.
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