Pressure is defined as the force exerted perpendicular to an object’s surface per unit area across which that force is dispersed. Solids can exert pressure on each other. Not only that but liquids and gases also exert pressure on solids. This article talks about the pressure exerted by water on different objects.

Water Pressure

Water pressure is the force that is exerted per unit area on the surface of an item in a perpendicular direction. Pascal(Pa) is the SI unit of water pressure. The term water pressure is also used to describe the strength of the flow of water through pipelines.

Water Pressure Formula

P = ρ × h × g

where,  

• ρ denotes the water density
• h denotes the height in meters
• g denotes the acceleration due to gravity

Water Pressure Loss

Pressure loss is a consequence of resistance to flow. It is given by the following formula:

L = 0.4335h

where h denotes the height of the said source/container.

Sample Problems

Problem 1. Calculate the pressure of water at the bottom of a tank of height of 6 m.

Solution:

We know, ρ = density of water = 1000 kg/m³

P = ρ × h × g

Here, h = 6 m and g = 10 m/s²

⇒ P = 1000 × 6 × 10

P = 60000 Pa

Problem 2. Determine the pressure loss of a waterfall of the height of 500 m, when it reaches the surface.

Solution:

Pressure loss is given by: L = 0.4335h

Here, h = 500 m

⇒ L = 0.4335 × 500

L = 216.75 Pa

Problem 3. Calculate the pressure of water at the bottom of a tank of height of 7 m.

Solution:

We know, ρ = density of water = 1000 kg/m³

P = ρ × h × g

Here, h = 7 m and g = 10 m/s²

⇒ P = 1000 × 7 × 10

P = 70000 Pa

Problem 4. Determine the pressure loss of a waterfall of the height of 800 m, when it reaches the surface.

Solution:

Pressure loss is given by: L = 0.4335h

Here, h = 800 m

⇒ L = 0.4335 × 800

L = 346.8 Pa

Problem 5. Determine the pressure loss of a waterfall of height 1200 m, when it reaches the surface.

Solution:

Pressure loss is given by: L = 0.4335h

Here, h = 1200 m

⇒ L = 0.4335 × 1200

L = 520.2 Pa