I did a lot of browsing and searching, to find nothing regarding this.

>Assume a body submerged in water (or any liquid for that matter). When we draw the FBD, we show the buoyant force, the weight of the object. These two forces simulate and determine whether the object sinks or floats (neglecting viscosity and other non-ideal conditions).

My question is, why don't we also include the weight of water with these two forces?

[![enter image description here][1]][1]


Another question i had was how do your find the force on an object(say cylinder) at a depth $h$ without using any imaginary cylinders (using pure mathematics and fbd's, please do not answer saying that F= Area*Pressure at that point = $A*hpg$). My approach was something like this

[![enter image description here][2]][2]

  [1]: https://i.sstatic.net/FyUREy9V.png
  [2]: https://i.sstatic.net/M6TGlxSp.png

As you may guess it gets pretty messy and doesnt really work.