# Pressure changes of a fluid flowing through a horizontal pipe

• Photo1234
In summary, the conversation discusses the relationship between pressure difference and fluid flow, and the application of Ohm's law in a circuit. It is concluded that pressure difference is necessary for fluid flow, and that 0/0 in Ohm's law does not have a physical meaning.
Photo1234
If we have a tube of fluid going like it is shown in the picture, and we measure pressure at two points we would get the same value. But the fluid is still going from point A to point B. So is pressure difference not necessary for fluid flow or I made some other wrong assumptions?

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Photo1234 said:
So is pressure difference not necessary for fluid flow
Newton's first law. An object in motion will continue in motion at a constant velocity unless acted on by an outside force.

If friction and viscosity is significant you will need a pressure gradient to drive the flow. If they are not, the pressure in the two points will be the same.

russ_watters and Chestermiller
What if we use electrons instead of fluid and use Ohms law V = R * I for two points like that, and If V = 0, that current should also be 0. Is that violation of Omhs law?
(We neglect resistance of the wire)

Photo1234 said:
What if we use electrons instead of fluid and use Ohms law V = R * I for two points like that, and If V = 0, that current should also be 0. Is that violation of Omhs law?
(We neglect resistance of the wire)

No it is not a violation and it does not need us to neglect the resistance. Let us say R=1, Then V=R*I means 0=1*0. Same answer if R=1000.

If we look at two points with the sam voltage in the circuit, then V=0, and R=0, but current flows.

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Did you understand the answer in post #3?

So I = V/R = 0/0

And what causes current if not voltage? Inertia?

Photo1234 said:
So I = V/R = 0/0

And what causes current if not voltage? Inertia?
You're trying to find a physical meaning for an assumed - not real - mathematical result of 0/0. There really isn't one. Stick to the physical laws. Stick to the answer you got in post #3 and recognize that simplifications are sometimes useful, but sometimes give nonsensical results.

russ_watters said:
You're trying to find a physical meaning for an assumed - not real - mathematical result of 0/0. There really isn't one. Stick to the physical laws. Stick to the answer you got in post #3 and recognize that simplifications are sometimes useful, but sometimes give nonsensical results.

What abaut this:
Photo1234 said:
And what causes current if not voltage? Inertia?

Sorry, this question has been answered several times.

@Photo1234 go back and re-read the answers.

Thread closed.

## 1. What causes pressure changes in a fluid flowing through a horizontal pipe?

The pressure changes in a fluid flowing through a horizontal pipe are caused by the velocity of the fluid and the resistance of the pipe. As the fluid moves through the pipe, it experiences friction against the walls of the pipe, which creates a pressure drop. Additionally, changes in the velocity of the fluid can also cause pressure changes, as faster moving fluid has a lower pressure compared to slower moving fluid.

## 2. How does the diameter of a pipe affect pressure changes in a fluid?

The diameter of a pipe has a direct impact on pressure changes in a fluid. A larger diameter pipe will have a lower resistance to flow, resulting in lower pressure changes compared to a smaller diameter pipe. This is because a larger diameter pipe allows for a greater volume of fluid to flow through, reducing the friction and pressure drop.

## 3. What is the Bernoulli's principle and how does it relate to pressure changes in a fluid?

Bernoulli's principle states that as the velocity of a fluid increases, the pressure decreases. This means that as a fluid flows through a horizontal pipe, the pressure will decrease as the velocity increases, and vice versa. This principle is important in understanding pressure changes in a fluid flowing through a horizontal pipe.

## 4. How does the viscosity of a fluid affect pressure changes in a horizontal pipe?

The viscosity of a fluid, or its resistance to flow, can also impact pressure changes in a horizontal pipe. Highly viscous fluids, such as honey, have a higher resistance to flow, resulting in larger pressure changes compared to less viscous fluids, such as water. This is because the friction between the fluid and the pipe walls is greater for more viscous fluids.

## 5. Can pressure changes in a horizontal pipe be controlled?

Yes, pressure changes in a horizontal pipe can be controlled by adjusting the flow rate, pipe diameter, and fluid viscosity. By increasing the flow rate, the pressure changes will also increase. Similarly, using a larger diameter pipe or a less viscous fluid will result in smaller pressure changes. Controlling these factors can help maintain a desired pressure in a fluid flowing through a horizontal pipe.

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