Now, I have explained about the evaluation of forces F x of k and z of k. And now, once you use this coefficients then you can arrive at the values of the forces moments etcetera. So, all these are equations, these above equations are. So, you have to be careful with a limit, that is being adopted here, for the evaluation of the flow coefficients. And these above coefficients are restricted to the following ranges. And these are all based on experimental investigations.