I would like to know whether my reasoning is ok. The problem is the following:
A horizontal cylindrical tank of radius $r = 4\ m$ and length $L = 10\ m$ is half full of water. What is the work done in pumping the water to the top of the tank?
Consider: $g = 10\ m\cdot s^{-2}$.
I calculate the center of mass when the water is in the down half, and the center of mass when it is in the upper half, and finally, I calculate the work with $W = mgh$, where I take $h$ as the distance between both centers of mass.
Is this approach correct?