The weight of a liquid pulls it down into it container causing pressure on the container and on any other object in the liquid.

Laws of Liquid Pressure

1. Pressure in a liquid increases with depth (h). The further down you go into a liquid the greater the weight on you and the higher the pressure.
2. Pressure does not depend on the shape of the container.
3. Pressure at one depth act equally in all directions. A liquid under pressure pushes on every surface in contact with it no matter which direction the surface is facing.
4. Pressure of a liquid depends on density (ρ). The greater the density, the higher the pressure.

Pressure in a liquid can be calculated from the formula below:

P= ρgh

Where P = pressure

ρ = density

h = depth

Example: Calculate the pressure exerted on a fish 10m below sea water of density 800kg/m².

Solution

P= ρgh                 But P= 800kg/m², g= 10m/s² and h=10m

P = 800*10*10 = 80000N/m²