Now this equation influid dynamics is known as placier's equation. And as long as we assume that the blood is incompressible and that the fluid is flowing, the blood is flowing in laminar or streamlined flow, then we can use this equation to study and understand the way that our blood flows inside our blood vessels. Now, why is this equation important? Well, this equation is important because it describes the volume flow rate to the resistance indirectly. So notice that we have a radius on the left side of the equation. And we know that the radius depends on the resistance, or the radius determines the resistance.