Hydrostatic Pressure

The term ‘hydrostatic pressure’ likely already has your mind working in overdrive. Far from being an everyday term, this important scientific phrase defines the pressure of a liquid on its ‘container’ or whatever happens to be surrounding it.

It’s vital for anyone working in any industry that uses water, such as plumbers, water treatment agents, and even dam inspectors.

The Principle

Liquid and gas particles all exert pressure over a given area. A solid doesn’t because its molecules are already held in one place.

But liquid and gas particles act in a different way. Gas particles will fill a container, bounce off each other and the container. The pressure of a gas is always the same over the entire area.
On the other hand, a liquid will fill its container, but it will always be bonded together. The fluid is pulled down by gravity, so the pressure exerted is different as you move throughout the liquid and the container. It’s why the pressure of an ocean is much higher on the floor than it is towards the surface.

Calculating Pressure

So now that we understand the principle of hydrostatic pressure, we have to think about how we’re going to calculate it.

When using the equation, we never calculate it when it’s moving. If it’s flowing, the pressure can change all the time. If it’s stable, we can calculate the pressure at any given depth. The equation we’ll appear as P =? * g * d
It looks complicated, but all you have to do is plug in the numbers. Each aspect of the equation is listed below:
P = pressure.
? = density.
G = gravity.
D = depth.

A Note on Depth

A liquid’s pressure doesn’t change based on the depth. It sounds like a contradiction, but it’s true. The change in pressure happens because of gravity not depth.

The reason for this is because liquids aren’t compressible. The molecules are already close to each other. It’s why in a sealed container it’s impossible to push the liquid together beyond a certain point. The molecules have filled all available space.

Working it All Out

Working out hydrostatic pressure doesn’t have to be as difficult as it looks. Through using this guide to get started, you’ll discover it’s all a matter of putting the numbers in and seeing what comes out the other side.

You’ll find this to be one of the most useful equations whether you’re a science student or someone working in the profession.