(adsbygoogle = window.adsbygoogle || []).push({}); Volume Flow Rate, Help???

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

The volume flow rate in an artery supplying the brain is 3.5E-6 m^3/s.

(a.) If the radius of the artery is 5.4E-3 m, determine the average blood speed.

(b.) Find the average blood speed at a constriction in the artery if the constriction reduces the radius by a factor of 7. Assume that the volume flow rate is the same as in part (a.)

2. Relevant equations

Q = Volume flow rate = AV

3. The attempt at a solution

I got (a.) but I need help with (b.). I think my radius for part (b.) is wrong, but I don't know how else to get it.

For part (a.) I got 0.0382 m/s by using

Q = Volume flow rate = AV = pi x r^2 x v = 3.5E-6 m^3/s

and using the given radius in part (a.) I solved for v.

For part (b.) I divided the given radius by 7, and subtracted that from the original radius to get a radius of 4.63E-3, and I put it into the equation the same way as part (a.) and I got 0.0520 m/s, but it's wrong. Help?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Volume Flow Rate, Help?

**Physics Forums | Science Articles, Homework Help, Discussion**