1. Mar 25, 2013

### Stretch999

1. The problem statement, all variables and given/known data
Help! How to find the difference in height in a u shaped tube?
1. The problem statement, all variables and given/known data

The horizontal pipe, shown in the figure, has a cross-sectional area of 40,0cm2 at the wider portions and 10,0cm2 at the constriction. Water is flowing in the pipe, and the discharge from the pipe is 6,00∗10−3m3s(6,00Ls). The density of mercury is ρHg=13,6∗103kgm3 and the density of water is ρw=1,00∗103kgm3.
Find
a)the flow speeds at the wide and the narrow portions
b)the pressure difference between these portions
c) the difference in height between the mercury columns in the U-shaped tube?

hint(Express the pressure at the lower mercury-water interface in two ways and uzse these expressions to solve for h)

1 minute ago
- 4 days left to answer.

This is the image of the situation:
http://session.masteringphysics.com/problemAsset/1260675/1/YF-14-45.jpg

2. Relevant equations
for a) i use AV=volume flow rate
b)used Bernoullis eqn and made the heights 0
c) used p=p1 and p=p2+density*g*h

3. The attempt at a solution
a) got v at large area=6m/s
v at constricted area=1.5m/s
b)got difference in presure to be 16875pa
c)got 0.127m which is apparently wrong
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Mar 25, 2013

### SteamKing

Staff Emeritus
Shouldn't the velocity in the constricted area be higher than the rest of the pipe?

3. Mar 26, 2013

### Stretch999

Sorry i typed it in wrong they are the other way round
velocity at the constricted is 6m/s
velocity at the large is 1,5m/s

4. Mar 26, 2013

### Sunil Simha

Did you use Bernoulli's equation of flow to get the pressure difference?

5. Mar 26, 2013

### Stretch999

1. The problem statement, all variables and given/known data[/b]
Help! How to find the difference in height in a u shaped tube?
1. The problem statement, all variables and given/known data

The horizontal pipe, shown in the figure, has a cross-sectional area of 40,0cm2 at the wider portions and 10,0cm2 at the constriction. Water is flowing in the pipe, and the discharge from the pipe is 6,00∗10−3m3s(6,00Ls). The density of mercury is ρHg=13,6∗103kgm3 and the density of water is ρw=1,00∗103kgm3.
Find
a)the flow speeds at the wide and the narrow portions
b)the pressure difference between these portions
c) the difference in height between the mercury columns in the U-shaped tube?

hint(Express the pressure at the lower mercury-water interface in two ways and uzse these expressions to solve for h)

1 minute ago
- 4 days left to answer.

This is the image of the situation:
http://session.masteringphysics.com/problemAsset/1260675/1/YF-14-45.jpg

2. Relevant equations
for a) i use AV=volume flow rate
b)used Bernoullis eqn and made the heights 0
c) used p=p1 and p=p2+density*g*h

3. The attempt at a solution
a) got v at large area=1.5m/s
v at constricted area=6m/s
b)got difference in presure to be 16875pa
c)got 0.127m which is apparently wrong

6. Mar 26, 2013

### Stretch999

Yes i did you and made the heights 0 because they on the same level.

7. Mar 26, 2013

### Sunil Simha

I can't see what is wrong with your calculations. They seem legitimate. What are the expected answers for pressure and velocities in your source?

8. Mar 26, 2013

### Stretch999

I don't know that's the problem. I thought it was wrong because someone said that they got this answer and apparently it was wrong but now that you confirmed what I thought maybe he was wrong. Thanks