Hello I am having difficulty in comprehending the basics of fluid mechanics . I have few questions which I would like to put one at a time , so as not to create any confusion . In the following attachment , a container with a liquid rests on a surface .I would like to understand what are the forces acting on a liquid molecule(marked in red) at the surface. 1.Atmospheric Pressure P0 acting vertically downwards(Purple) 2.Pressure from the surrounding liquid Psur acting vertically upwards(black) 3.Weight of the particle W acting vertically downwards(green) Is it correct to say Psur = P0 + W ? But pressure at the surface due to surrounding liquid Psur should be equal to P0 . Does that mean we neglect W ? Edit :The red dot represents a liquid molecule at the surface .