# Relationship between pressure and volume in fluids

### How does pressure affect density of fluid?

Pressure and velocity have an inverse relation an example pumps are used to to increase the velocity of the fluids in case when water flows from a river to a. Gases: If the fluid is a gas (and if the temperature remains constant), pressure is inversely proportional to volume for a given mass of gas, ie PV = C where C is a. Its not the velocity of fluids. Its the volume and pressure relation. I think you'r looking for BOYLE's law. Its an ideal gas law- applicable to all.

By static pressure I do not mean hydrostatic - I mean static as in the other pressure factor of water not sure what it is called.

## Pressure, temperature, and volume relation in liquids

Your water company decides, whelp, let's increase the city water pressure! Say originally we had a horizontal copper pipe full of water.

At the one end of the pipe is a tap that is closed.

**Pressure at a depth in a fluid - Fluids - Physics - Khan Academy**

At the other end of the pipe is the incoming city water company city pressure. Water temperature is 20 degrees celsius room temp in the pipe originally, and a pressure of "1". Then the city increases water pressure to "2". The units do not matter, just say the pressure doubled.

The water did not move, because the tap was shut.

Yet the static pressure doubled. Technical 9 years ago Skipper, you have not spoken about the Centrifugal Pump Involute Casing, and the change of velocity head to pressure head there, yet. I think you're "keeping" the notion of gas pressure and applying it to pressure of a fluid.

The flow of gases is a compressible flow. And I very well understand the difference between Compressible and Incompressible flow concepts. And I am strictly speaking about the Incompresible flows in liquids. If you increase the fill rate the level in the bucket goes up, and passes the outflow rate.

## What is volume flow rate?

Pressure at the outlet is determined by the surface area of the water in the bucket, the higher it goes the higher the outflow rate. Flow pressure at the hole equals surface pressure cross-section of container.

The pressure of water at any level would simply be the Height of Water Column, and the pressure is same for the same height and is equally tramsmitted in all directions this the beauty of hydraulics. The forces normal to the inner surface of the bucket, all pointing inwards, 'react' to the pressure by 'expelling' water from the hole.

Flow out of the hole is the water 'reacting' to these forces.

### Fluid dynamics and Bernoulli's equation

And the Outflow rate is not the function of surface area, but simply the height of the water column above the hole. Higher the water column higher the pressure. It is only the pressure acting at the particular height which causes the water to flow out as soon as it finds an opening and the constrain is removed the hole in this case.

The concept of pressure is closely related to the important characteristics of a flowing fluid. The Power of Pressure The technical definition of pressure is force per unit area. Pressure can be more meaningful than related quantities, such as mass or force, because the practical consequences of various scenarios are often dependent primarily on pressure. For example, if you use your fingertip to apply a mild downward force to a cucumber, nothing happens.

If you apply that same force with the blade of a sharp knife, you slice through the cucumber. The force is the same but the edge of the blade has a much smaller surface area, and thus the force per unit area -- in other words, the pressure -- is much higher. Flowing Forces Pressure applies to both fluids and solid objects.