 So the last thing that von Karman calculated with his momentum integral analysis was the friction coefficient. And the friction coefficient, just like any of the coefficients typically that we use in fluid mechanics, it was 2 times tau wall divided by rho u out of the square. So basically the dynamic pressure, 1 half rho u squared in the denominator. And what he did is he substituted the value for the wall shear stress that he got from the control volume analysis. And he also substituted in here his quadratic velocity profile. And in doing that, he came up with this for the friction coefficient. So we have a few things here, u naught, u naught that cancels. We have a mu over rho, and that is our kinematic viscosity. And then finally what we have is we have delta, and delta is the boundary layer thickness. So what he then did is he took the boundary layer thickness that he just calculated, that we looked at in the previous section. So let's introduce that and see what we get for the skin friction coefficient. So that is what von Karman ended up with for the friction coefficient. So you can see he was able to get pretty far using momentum integral analysis, a very simple tool that we have learned in this course. The only approximation that he had to make in going through this analysis was the velocity profile itself, and for that he assumed it to be a quadratic function. And that was really the only place where there was an approximation made, and we'll see that that was a bit of an off approximation, but it wasn't too far off, but it enabled him then to get the delta, so the growth of the boundary layer thickness, as well as the friction coefficient, two very important engineering parameters. So what we'll be doing in the next segment, or next lecture I should say, is we'll be looking at the technique that Prandtl came up with, and actually it was his graduate student Blasius, who came up with a differential equation. He took Navier-Stokes and made some approximations, the boundary layer approximations, and ended up with the set of equations that he integrated by hand, and got his PhD for that. But it gave him a relationship for this, as well as this, and what we'll do is we'll compare that to the results that von Karman was able to obtain. So that is the Karman integral method. What we'll do in the last segment in this lecture is just look at the two definitions, one being momentum thickness, and another one is displacement thickness, which are quite often used to characterize the shape and provide a parameter for shear layers in general, but specifically for wall-bounded shear flows or boundary layers that we're looking at in this lecture here. So that's how we will close the lecture, and then we'll move into Prandtl's analysis in the next lecture.