When Reynold's number Re exceeds about 2000, fluid flow becomes turbulent. A physician can detect turbulent flow in the heart using sound waves. In this task, you will estimate how much narrowing from plaque needs to occur before fluid flow becomes particularly turbulent.

In a typical person, with each passing minute, about 5 liters of blood, of density 1050 kg/m 3 and viscosity 3.510 3 Pa s, move through the aorta, of diameter 0.020 m. (a) Calculate the mean speed of blood flow through the aorta at the threshold of turbulence, Re = 2000. Use the diameter of the aorta as the "characteristic length." (b) Use the continuity equation to estimate by what % the radius of the aorta would have to decrease due to plaque buildup to reach the threshold of turbulence.