Pressure In Liquids:

Have you study or been told that liquid water cannot be compressed? In a simplistic logic, this is true, though it doesn't mean liquid water never applies pressure. Liquids can and do apply pressure, as anyone who has been in a hurricane or a flood or a submarine will tell you. You can experience "water pressure" for yourself by diving down numerous feet in a swimming pool and noting the sensation the water generates as it presses against your eardrums.

In a fluid, the pressure that is defined in terms of force per unit area is directly proportional to depth. Pressure is also directly proportional to the weight density of the liquid. Assume d_w be the weight density of a liquid (in newtons per meter cubed), and assume s be the depth below the surface (in meters). Then the pressure P (in newtons per meter squared) is specified by

P = d_ws

When we are given the mass density d_m (in kilograms per meter cubed) instead of the weight density, the formula is as follows:

P = 9.81d_ms