Pressure vs speed for liquids ?

In summary, the conversation discusses the relationship between pressure and speed for liquids, using the example of a pipe with varying widths. Through the application of conservation of mass and Bernoulli's equation, it is determined that incompressible fluids flow faster in narrow sections, causing a pressure difference. This supports the inverse proportion of speed and pressure for liquids.
  • #1
furkang
9
0
pressure vs speed for liquids ? :(

Think of a pipe positioned horizontally.

Some fluid is flowing from left to right.(e.g. water)

Right side of the pipe is well narrower than left side.

Is the speed of a fluid particle at the right greater than the speed of a particle at the left?
What about their pressures?

(Perfect world no energy loss)
OR


perhaps I can NOT make such a comparison without considering any value constant.

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I am really confused please help , basically I am looking for an example which prooves inverse proportion of speed and pressure of LIQUIDS. Can you give me an example like mine? Thank you for your help...
 
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  • #2
Let's assume an incompressible fluid - the density does not change - and apply conservation of mass.

[itex]\rho_1 * V_1 * A_1 = \rho_2 * V_2 * A_2 [/itex]

for incompressible flow [itex]\rho_1 = \rho_2 = \rho [/itex]

which then leaves [itex]V_1 * A_1 = V_2 * A_2 [/itex]

So what does the say about the relationship between fluid velocity (speed) and area?
 
  • #3
ok that's well ...

that means fluid flows faster in the narrow section. That is completely different from my thought.
 
  • #4
Is it the same if we use Bernoulli's equation to see that?

I could't see where is the pressure difference
 
  • #5
Considering the fluid is incompressible, helps by making density constant. Is it the pressure difference, that causes the fluid to flow faster at the place where the pipe narrows?
 
  • #6
You should take it the other way round(you should obviously apply Bernoulli's equation), that static head drop occurs due to increase in velocity head.
 

1. What is the relationship between pressure and speed for liquids?

The relationship between pressure and speed for liquids is known as Bernoulli's principle. This principle states that as the speed of a fluid (such as a liquid) increases, the pressure exerted by that fluid decreases. Essentially, when a fluid is moving faster, the particles in the fluid are more spread out, resulting in less pressure.

2. How does the density of a liquid affect its pressure-speed relationship?

The density of a liquid does not directly affect its pressure-speed relationship. However, denser liquids may require more pressure to achieve the same speed as less dense liquids, due to the increased number of particles in the denser liquid.

3. What factors can affect the pressure-speed relationship of a liquid?

The pressure-speed relationship of a liquid can be affected by the viscosity (thickness) of the liquid, its temperature, and the shape of the object it is moving around. Other factors such as gravity and external forces may also play a role.

4. How is the pressure-speed relationship of liquids used in real-world applications?

The pressure-speed relationship of liquids has many practical applications, including in the design of airplane wings and water turbines. It is also used in hydraulic systems, where the pressure created by a liquid can be used to move heavy objects or perform work.

5. Is the pressure-speed relationship of liquids the same as that of gases?

No, the pressure-speed relationship for gases follows a different principle known as the ideal gas law. While both liquids and gases can experience changes in pressure and speed, the underlying principles and equations used to describe them are different.

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