this question is from renewable energy sources.

The wind after it passes through the area swept by the turbine blades.

a$.$ Assume that $V_1>0,$ give a physical explanation to show that $0\frac{V_2}{V_1}1.$

b$.$ The amount of power extracted from the wind depends upon the ratio $x=\frac{V_2}{V_1}.$ Prove that maximum power extraction is at $V_2=\frac{V_1}{3}.$ Calculate $x(1)$ and explain how you could have arrived at the value $V_2=\frac{V_1}{3}$ without using the formula for x $.$

c$.$ Give a physical explanation of why it is unlikely or impossible for it to be the cause that $x=1.$

d$.$ Give a physical explanation of why it is impossible at $x=0$ to have any Power