Height of fluid and Bernoullis equation

In summary, the conversation is about calculating the height difference of a liquid in two vertical pipes connected to a horizontal pipe. Bernoulli's equation is used, along with the continuity equation, to solve for the height difference. The correct answer is found to be 0.4 m. The book's answer of 4x10-3 m is determined to be incorrect due to a missing decimal in the initial velocity.
  • #1
radiator0505
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Homework Statement



An ideal liquid flows horizontally through a pipe of cross sectional area 3cm2 with a velocity 1ms-1. The pipe narrows to a cross sectional area 1cm2. 2 vertical pipes are connected to the pipe, one in either region.
Calculate the height difference of the liquid between the 2 vertical pipes.


Homework Equations



p1 + 0.5ρv12 + ρgh1 = p2 + 0.5ρv22 + ρgh2

A1v1 = A2v2


The Attempt at a Solution



I think I'm a bit confused on what my variables represent in bernoullis equation:
Using the continuity equation gives v2 = 3ms-1.
Then I said that for the pipes p1 = p2 (because they're both open to the atmosphere), putting everything into bernoullis equation and rearranging gives
h1 - h2 = 0.4 m
The book says the answer is 4x10-3 m.

Am I not allowed to consider the heights of the fluid in the vertical pipe because I calculated the speeds of the fluid in the horizontal pipe? I can't think of any other way to do the problem.
 
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  • #2
Oh sorry nevermind, I got it.
Turns out the velocity is initially 0.1 ms-1, then doing what I said gives the answer.

:)
 
  • #3
IMO, the book's answer is wrong.

I see that the OP had missed a decimal in the initial velocity. Book answer is OK.
 
Last edited:

Related to Height of fluid and Bernoullis equation

1. What is the height of fluid?

The height of fluid refers to the vertical distance of a liquid or gas from its lowest point to its highest point within a container.

2. How is the height of fluid related to Bernoulli's equation?

Bernoulli's equation states that the total energy of a fluid in motion is constant. This includes the potential energy of the fluid due to its height, which is related to the pressure and velocity of the fluid.

3. Can the height of fluid affect the pressure of the fluid?

Yes, the height of fluid can affect the pressure of the fluid. According to Bernoulli's equation, the higher the height of fluid, the lower the pressure will be, and vice versa.

4. How does the height of fluid impact the velocity of the fluid?

The height of fluid is directly related to the velocity of the fluid. As the height of fluid decreases, the velocity increases and vice versa. This is because the potential energy of the fluid is converted into kinetic energy as it flows downhill.

5. What factors can affect the height of fluid in a container?

The height of fluid in a container can be affected by several factors, including the volume of fluid, the shape of the container, the speed of the fluid, and the gravitational force acting on the fluid.

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