Potential Energy of water in a wedge

[irkutsk]

Homework Statement

A symmetric wedge of depth h and width A is filled to the brim with water of mass m, where acceleraton due to gravity is g. What is the potential energy of the water with respect to the base of the wedge?

Homework Equations

E = mgh

The Attempt at a Solution

E = 0.5*mgh for a cylinder (integrating as the force of any given disc increases linearly from 0 to gh between h=0 and h=h). But I'm having a mental block with how to integrate when the horizontal cross-section increases linearly from 0 to A as h goes from 0 to h. Thanks :D

 

[barryj]

How about this: Where is the center of gravity of this triangle, and how far above the base is it?