# How can I calculate h from this diagram

1. Dec 5, 2014

### Furious

• Member warned about not using the homework template

Water flows in the horizontal pipe shown in Fig. 13-6. At A the area is and the speed of the water is At B the area is 16.0 cm2. The fluid in the manometer is mercury, which has a density of What is the manometer reading h?

My attempt:
I used A1V1 = A2V2 to find the speed at B which is 3.125
Then I used Bernoulli equation and I have: P(A) = P(B) + 2883

Last edited by a moderator: Apr 18, 2017
2. Dec 5, 2014

### Staff: Mentor

In future, please retain and use the formatting template provided when you start a thread in the homework areas.

Assuming that you have the correct pressure difference between A and B then if you assume some cross-sectional area for the mercury tubing you should be able to assign forces at the mercury surfaces. Since the mercury is in equilibrium, something needs to balance out the forces applied at the surfaces...

Last edited: Dec 5, 2014
3. Dec 5, 2014

### Staff: Mentor

Last edited: Dec 5, 2014
4. Dec 5, 2014

### Furious

p(a) is applied on left side and on right side p (a) - 2883 but what is the next step?

5. Dec 5, 2014

### Staff: Mentor

What might cause a change in pressure with height (or depth) in a fluid?

6. Dec 6, 2014

### rude man

You know p1 - p2. Just apply Bernoulli again for the mercury in the U-tube. (You don't need to know the area of either side of the tube; in fact, they can be very different.)

Last edited: Dec 6, 2014