Raius of the Circular observation window is
.
Window is vertically in a large water tank.
\
.
Observe the figure :
\Consider the depth of the tank is
.
The circle equation is
.
Consider the center of the circular end of the tank is at origin.
\
.
The horizontal length of the tank is
.
Therefore,
.
The
ranges from
to
.
The fluid force is
.
(a)
\Find the fluid force on circular window when it is 3 feet below the water surface.
\Thus
.




Integral formula :
.



.
(b)
\Find the fluid force on circular window when it is
feet below the water surface.
Thus
.






.
Fluid force on a circular plate is
.
(a)
.
(b) Fluid force on a circular plate is
.