So let's say by increasing the radius, we decrease our resistance. And from this equation, if we increase the radius, we ultimately increase the volume flow rate. So what this means is if we increase the radius even by a small amount, we increase the volume flow rate by a much greater factor. And this can be seen from the following graph. So if we assume that l the length, the viscosity and the change in pressure is constant and we plot our relationship this equation, we basically get the following curve. Now the y axis is the relative volume flow rate Q and the x axis is the relative radius given by lowercase r. So from this relationship we see that even a tiny change in the radius can greatly increase the relative flow rate of our blood.