Question

an artificial heart valve was tested for its ability to function under extreme conditions, to a maximum flow rate of 4.00 x 10-4 m3/s. what speed would this correspond to for an average red blood cell within a blood vessel of cross-sectional area 5.00 x 10-6 m2? a. 2.00 x 10-9 m/s b. 1.25 x 10-2 m/s c. 4.05 x 10-4 m/s d. 8.00 x 101 m/s'

Answer 1

We can work with units to solve this, the flow rate is 4x10^-4 m^3/s and the area is 5x10^-6 m^2

If we divide the flow rate by the area, the units will cancel like this, m^3/(s*m^2) which will give a unit of m/s which is the unit of speed.

So dividing the flow rate by the area:
(4x10^-4)/(5x10^-6) = 80, so d should be the answer

Good luck and hope this helps