Blood Pressure Difference between Aorta and Aneurysym

[dvolpe]

Homework Statement

Blood flowing thru aorta (radius 1.2 cm) enters aneurysym of radius 3.1 cm. How much on average is blood pressure higher inside the aneursym than the pressure in the unenlarged part of aorta? Average flow rate of blood thru aorta is 110 cm cubed/sec

Homework Equations

Q = flow rate = speed * area = speed* pi* r squared
P1-P2 = 1/2*p*(V2 squared - V1 squared)

The Attempt at a Solution

First calculated V1 (aorta) = 110 cm cubed/s/ Pi*((1.2 cm)squared) = 24.35 cm/s = .2435 m/s

Q1 of aorta = Q2 of aneursym
Q1 = 110 = V2*(pi*r2 squared)
V2 =110/pi*(3.1)(3.1)
V2 = 3.64 cm/s = .0364m/s

P1-P2 = 1/2*1060*[(.243*.243) - (.0364*.0364)] = 530 (.0590 - .00132) = 530 (.05768)
P1-P2 = 30.57 Pa

Is this logic and answer correct? I need help ASAP! Thanks.

NOTE: When I submitted this answer online, it was correct!

 

[anathema]

Your logic and answer seem to be correct. You have correctly used the equations for flow rate and pressure difference to calculate the difference in pressure between the aorta and the aneurysm. However, it is always a good idea to double check your calculations and make sure all units are consistent. Also, it would be helpful to include units in your final answer (30.57 Pa) to make it clear that it is a pressure difference. Overall, good job on your solution!