Question

If a fluid has a higher pressure, what can you say about the speed of the liquid?

Answer 1

Good question, and tough to answer, as you can see from your responses.

A fluid (liquid, or gas) is composed of atoms/molecules ('particles'). I'll refer to a liquid here.....when sitting idle the 'particles' in a liquid (like in a glass of water) are free to move about essentially in equilibrium in all directions macroscopically speaking (large-scale --- you-and-I-scale). This accounts for equal pressure being exerted in all directions in the liquid (fluid). The motion of the particles is what gives rise to pressure, and pressure is just a force acting per unit of area.

This concept is standard in thermodynamics and usually in reference to an average kinetic energy of the particles as a whole, the value of which is not important here. But this energy is when a particle hits the container wall and imparts some of this energy to the container....it's individual contribution of pressure of the liquid as a whole.......make sense??? Add up all these individual 'hits' to the container for the whole fluid and voila`...you have what we perceive as pressure.

If you now take this liquid and send it traveling in one (predominant) direction, you cause all the motion ((predominantly) to be in this one direction. Therefore you necessarily reduce the pressure exerted in the other directions.

Friction in the liquid is not the same throughout the volume of the liquid. It varies because of friction with the sides of the transport media (tubing, hose, pipe, creek bed, river bed, etc), and also due to friction with its self.

This low pressure causes certain effects in the liquid and in neighboring fluids (liquids or gases). For example....water in your shower causes the shower curtain to draw up toward you...which is a royal pain. The lower pressure created by each stream adds and creates an overall effect of lower pressure of the shower spray as a whole. The reason this happens is because the speed of each stream causes the air in the vicinity of each stream to also speed up in the direction of the water, thus lowering the pressure in this region, causing the higher pressure air adjacent to it to rush inward to take the place of the lower pressure air being carried along by the water. This then becomes a cycle which gives the overall effect of what you see in the shower of the curtain being drawn inward to you.

This is where the high/low pressure stuff comes from and it's actually easy to see how this happens, but the key is knowing the liquid (fluid) is made of particles and that their movement in the fluid is what gives rise to the pressure. Making the fluids move...causing these particles to move, necessarily has to influence the pressure, as I described.

Hope this makes sense.

Answer 2

or

Answer 3

Q = Area x Velocity and Also, Q = (pie x r^4 x Pressure)/ 8* Length * Viscosity, There fore

Area x Velocity = (pie x r^4 x Pressure)/ 8* Length * Viscosity

So, Pressure is Inversely Proportional to the velocity that what formula explains it.