The equation is
.
The base of the plate is
beneath the surface of the water.

Observe the graph:
\The height of the vertical plate is
.
The horizontal length of the vertical plate is
.



.
Therefore,
.
The fluid force is
.
The limits are
to
.
The weight density of water is
.
Substitute
,
and
.
.
Consider the integrand as function
.
Graph the function
.
.
Observe the graph:
\
.
.
Therefore,
.
.