physics, I'm stuck

In an aortic aneurysm, a bulge forms where the walls of the aorta are
weakened. If blood flowing through the aorta (radius 1.0 cm) enters an aneurysm with a radius of 2.5 cm, how much on average is the blood pressure higher inside the aneurysm than the pressure in the unenlarged part of the aorta? The average flow rate through the aorta is 120 cm3/s. Assume the blood is nonviscous and the patient is lying down so there is no change in height.
A. 150 kPa B. 75Pa C. 75 kPa D. 62 Pa E. 750 Pa

So I thought I was on the right track, I found the area of both the normal blood vessel, and where the aneurysm is using A=pi*r^2 for A1= 3.142 and A2= 19.63, then I used rate flow=A1v1=A2v2 to find the velocity in both. I got v1= 38.20 and v2= 6.116.

I know I should somehow use Bernoulli's equation, or I think I should, but I have no idea what to do now.

Any help would be appreciated!

Thanks

  1. 👍 0
  2. 👎 0
  3. 👁 63
asked by trace
  1. The dimensions of your velocities are cm/s and you have used the continuity equation correctly to get the two velocities.

    You are correct that the Bernoulli equation is what you need to compute the pressure difference. It is only valid if viscous effects can be neglected, which is OK over such a short distance. With no difference in height,
    (p2 - p1) = (1/2)(density)(V1^2 - V2^2)
    Use 1.06 g/cm^3 for the density of blood.

    p2 - p1 = (0.5)(1.06)[38.2^2 - 6.1^2] = 746 dyne/cm^2 (round to 750)
    = 7.5*10^4 Pa = 75 kPa

    That is quite high, about 3/4 atmosphere. No wonder people die of ruptured aneurysyms

    1. 👍 0
    2. 👎 0
    posted by drwls
  2. .. for showing your own work. We encourage students to do that here, but very few do.

    1. 👍 0
    2. 👎 0
    posted by drwls
  3. thanks!

    1. 👍 0
    2. 👎 0
    posted by trace
  4. thanks!

    but when i checked the conversion online, 750 dyne converts to 75 Pa, not 75kPa, which conversion is correct?

    Is there a reason you have a different conversion, that I'm not seeing?

    1. 👍 0
    2. 👎 0
    posted by trace
  5. 1 Pascal = 1 N/m^2
    = 10^5 dyne/10^4 cm^2
    = 10 dyne/cm^2

    You are quite right. My conversion was wrong.

    1. 👍 0
    2. 👎 0
    posted by drwls
  6. thank you so much!

    Have a good night

    1. 👍 0
    2. 👎 0
    posted by trace

Respond to this Question

First Name

Your Response

Similar Questions

  1. Anatomy and Physiology

    when the aortic valve opens into the aorta blood flows A. out of the body B. into the right atrium *** C. into the left ventricle D. out of the pulmonary artery my answer : C Am i correct?

    asked by Lolaw on January 23, 2017
  2. Physics

    The blood flow rate through the aorta is typically 103 cm^3/s, and a typical adult has about 4.9 liters of blood. (a) How long does it take for all your blood to pass through the aorta? ___________s (b) If your aorta has a

    asked by Alex on June 6, 2012
  3. Anatomy and Physiology

    Hello! Thanks for checking my question! ____ 15. When the aortic valve opens into the aorta, blood flows (1 point) a) out to the body. b) into the right atrium. c) into the left ventricle. d) out of the pulmonary artery. My

    asked by Da Fash on November 9, 2017
  4. Medical Coding

    Operative Report Pre-Operative Diagnosis: Rheumatic aortic stenosis Procedure Performed: Valvuloplasty, aortic valve with transventricular dilation Operative Note: This 38-year-old female patient who has a diagnosis of rheumatic

    asked by Cuki on January 4, 2010
  5. music

    Quincey Jones had a berry aneurysm - not a beri aneurysm didn't he?

    asked by Anna on April 3, 2008
  6. bio

    name three major blood vessels that branch off the aortic arch and the body part the blood is carried to name two major artries that branch off the dorsal aorta and the organ they carry blood to

    asked by Annie on January 22, 2012
  7. biology help?

    Please tell me which one is TRUE or FALSE for the statements below: 1. During the cardiac cycle the pressure in the left ventricle and right ventricle are approximately equal. 2. During isovolumetric contraction the left

    asked by sam on October 10, 2013
  8. biology help plz?????????????????

    Please tell me which one is TRUE or FALSE for the statements below: 1. During the cardiac cycle the pressure in the left ventricle and right ventricle are approximately equal. 2. During isovolumetric contraction the left

    asked by sam on October 10, 2013
  9. English

    How do you paraphrase this statement? A brain aneurysm is a ballooning-out of the wall of an artery in the brain. Often this wall is weakened by disease, injury or an abnormality present at birth. Aneurysms are often caused or

    asked by kanae on June 4, 2008
  10. Physics

    The human heart is a mechanical pump. The aorta is a large artery that carries oxygenated blood away from the heart to various organs in the body. For an individual at rest, the blood in the aorta (of radius 1.25 cm) flows at a

    asked by Johnny on January 17, 2013

More Similar Questions