(1) Integral formula:

F=abρgh(y)w(y)dy

Option 1:

(2) Using y=0 at water line, increasing downwards: (a) Left:

F=15ρgy(222(y3)2)dy

(b) Center:

F=03ρgy(232y2)dy

(c) Right:

F=02ρgy(242(2y)2)dy

Option 2:

(2) Using y=0 at center of shape, increasing downwards: (a) Left:

F=22ρg(y+3)222y2dy

(b) Center:

F=03ρgy(232y2)dy

(c) Right:

F=20ρg(y+2)242y2dy