A) In the case of the Boundary Thickness Layer we use the given formula,

We know as well that,
Re = Número de Reynolds = 
Where,
U = velocity
= kinematic viscosity
For water, kinematic viscosity, 
So, 



B) For flat plate boundary layer. Given the Critical Reynolds Number.= 5*10^5 we know that is equal to Re above.
Thus, 
C. Wall shear stress,

For water, dynamic viscosity,
= 2.344*10^-5 lbf-s/ft^2


P= w/t and W= Work
In this case, W= 6,700j, and T= 45 seconds
Power is the ratio of work per unit time. When you perform a work in a given span of time, the ratio of work performed with respect to time is Called Power.
si unit for Power is Watt (W)
so, P= 6,700/45
P= 148
Final answer is P=148