 # Water Pressure Formula

## Water Pressure Formula

Pressure is defined as the force applied which is perpendicular to the surface of the object per area over which the force is distributed. The Gauge pressure is the pressure relative to ambient pressure. Various units are applied to express pressure. Some of which derive from a unit of force per unit area. The SI unit of pressure is Pascal (Pa). Similarly, water pressure is the term used to describe the strength of water flow through a channel or pipe.

The water pressure formula and SI unit are given as:

 Formula Water pressure= ρ g h SI unit Pa

Where,

• P = water pressure in Pa
• ρ = density of water in kg.m-3
• g = gravitational force in 9.81 m.s-2
• h = height in m

The loss of Water pressure can also be calculated.The water pressure loss formula due to height h is given as:

 Pressure loss = 0.4335 x h

Where,

• h denotes the height

### Solved Example

Example 1
A tank of height 6 m is filled with water. Calculate the pressure on the tank at its bottom.

Solution:
Given:

Density of water, ρ = 1000 kg/m3

Acceleration due to gravity, g = 9.8 m/s2

Height, h = 6m

The water pressure formula on the tank is given by,

P = ρ g h = 1000 × 9.8 × 6 = 58800 Pa.

Example 2
A waterfall has a height of 200 m. Determine the pressure loss when it reaches the surface.

Solution:
Given:

Density of water, ρ = 1000 kg/m3

Acceleration due to gravity, g = 9.8 m/s2

Height, h = 200 m

The pressure loss formula is given by Pressure loss = 0.4335 ×200 = 86.7 Pa.