At the hole in the side of the cylinder (where we'll call the elevation y2 ), the pressure will also be atmospheric pressure P0, since the hole is exposed to the atmosphere here also. wh...At the hole in the side of the cylinder (where we'll call the elevation y2 ), the pressure will also be atmospheric pressure P0, since the hole is exposed to the atmosphere here also. where again H is the height of the hole above the platform, and h is the height of the liquid surface in the cylinder above the hole.