# [difficult] bernoulli's equation

1. Nov 8, 2007

### Bob Loblaw

1. The problem statement, all variables and given/known data

In an aortic aneurysm, a bulge forms where the walls of the aorta are weakened. If blood flowing through the aorta (radius 1.1 cm) enters an aneurysm with a radius of 3.1 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 110 cm3/s. Assume the blood is non-viscous and the patient is lying down so there is no change in height.

? Pa

2. Relevant equations

P = 1/2 (d (V1^2 - V2^2))
where
d = density
V1 = initial velocity
V2 = final velocity

3. The attempt at a solution

to get V1 you have to use Flow rate / pi r^2. When I try to finish the equation, I notice that I need the density of blood but none is given in the text nor in the homework. Is there a way to solve this without knowing blood density? Or do I have to find a value online?

Could anybody help?

Last edited: Nov 8, 2007