# Need MORE Hmwk helpFluid mechanics, Fluids in motion, pressure

• LBRRIT2390
In summary, Bernoulli's equation is used to calculate the velocity of a fluid flowing through a constriction. There is no solution found yet.
LBRRIT2390
College Physics

## Homework Statement

The figure shows a section of a long tube that narrows near its open end to a diameter of 1.0mm. Water at 20celsius flows out of the open end at 0.020 L/s

What is the gauge pressure at point P, where the diameter is 4.0mm?

http://session.masteringphysics.com/problemAsset/1014234/7/jfk.Figure.P13.62.jpg

## Homework Equations

Bernoulli's equation

## The Attempt at a Solution

Same as my last post, no solution found yet. Please help me start and work through this problem.

Bernoullis here is quite simple and the basis for a venturi tube. In the initial frame you have lower kinetic energy and some potential energy from pressure, P. Some of that potential energy is traded for kinetic energy;

P1+1/2 rho(v^2)= P2 + 1/2 rho(v'^2). V' is the final velocity. From continuity of flow, the two velocities can be expressed as a ratio. That help?

Thank you so much for replying!
So I plugged in everything that I calculated so far and ended up with:
P1 = P2 +49805

I can't figure out how to find the pressure in the smaller diameter tube so I can plug that in. I know it should be easy...I have the flow rate and the diameter, but I'm stuck.

Variables I've used:
rho=1000kg/m^3
Velocity1 = 0.623 m/s
Area of Larger section: 0.0126m
Velocity2= 10m/s
Area of Smaller section: 0.00785m

So you need a numerical answer not expressed in terms of p?

Correct, a numerical value in Pascals. I think I need to incorporate the length of each section as well, not sure how though.

Well gauge pressure is relative to P. No length doesn't enter it unless you have frictional losses and data to compute these. More info would be given if it were needed.

What do you mean by gauge pressure is relative to P?

Do you think that I am on the right track with the progress I've made? P1=P2+49806

LBRRIT2390 said:
What do you mean by gauge pressure is relative to P?

Do you think that I am on the right track with the progress I've made? P1=P2+49806

I was not able to get the answer before my assignment was due, the answer was 8.2E5 Pa.

But thank you, I really appreciate your help.

## 1. What is fluid mechanics?

Fluid mechanics is a branch of physics that studies the behavior of fluids, which include liquids, gases, and plasmas. It involves the study of how fluids move, their interactions with different forces, and the effects of these movements on their surroundings.

## 2. What is the difference between fluids in motion and in rest?

Fluids in motion refer to the movement or flow of fluids, while fluids at rest refer to the state in which fluids are not moving or have no net flow. In fluid mechanics, both states are important to understand as they have different properties and behaviors.

## 3. How is pressure related to fluid mechanics?

Pressure is a key concept in fluid mechanics as it is the force per unit area exerted by a fluid on its surroundings. Changes in pressure can affect the movement and behavior of fluids, and understanding pressure is important in analyzing fluid systems and their dynamics.

## 4. What are some real-life applications of fluid mechanics?

Fluid mechanics has numerous applications in everyday life, such as in the design of airplanes and cars, the flow of blood in the human body, the functioning of pumps and turbines, and the behavior of ocean currents and weather systems. It is also essential in industries such as aerospace, automotive, and environmental engineering.

## 5. How can I improve my understanding of fluid mechanics?

To improve your understanding of fluid mechanics, it is important to have a strong foundation in mathematics, particularly calculus and differential equations. You can also read textbooks and attend lectures or workshops on the subject. Additionally, hands-on experimentation and problem-solving can greatly enhance your understanding of fluid mechanics.

• Introductory Physics Homework Help
Replies
6
Views
1K
• Introductory Physics Homework Help
Replies
10
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
8K
• Introductory Physics Homework Help
Replies
9
Views
1K
• Introductory Physics Homework Help
Replies
1
Views
1K
• Introductory Physics Homework Help
Replies
10
Views
4K
• Introductory Physics Homework Help
Replies
1
Views
2K
• Introductory Physics Homework Help
Replies
7
Views
1K
• Introductory Physics Homework Help
Replies
6
Views
4K
• Introductory Physics Homework Help
Replies
34
Views
2K