# Communicating vessels(experiement)

1. Oct 31, 2013

### Hepic

Lets say we have two bottles that communicate via a tube.
Level of water,will try to be the same at both bottles because If hydrosatic pressure is bigger at the one,will try after some seconds to become the same.(pushing down the water of bottle with the more watter).
So lets say that level of water is the same at both bottles.
Now,for example we take the first bottle and put that in bigger height(30 cm heigher than other bottle). We see that water from heigher bottle goes to bottle with less height. Hydrostatic pressure there is not because water were in the same level,but maybe now atomospheric pressure is active. Is correct that the heigher bottle has bigger atmospheric pressure,so it sends its water in the other bottle??

Sorry for my english. Thank you!!!

2. Oct 31, 2013

### HallsofIvy

Staff Emeritus
You are mistaken in saying "Hydrostatic pressure there is not because water were in the same level". You have to count the water in the tube connecting the two bottles.

(Strictly speaking the atmospheric pressure on higher bottle will be less than on the lower because there is less atmosphere above it- but with a difference of only 30 cm, that will be unnoticable.)

3. Oct 31, 2013

### Hepic

So,the heigher bottle has bigger hydrostatic pressure?

4. Oct 31, 2013

### Staff: Mentor

No. As HallsOfIvy said, you have to consider the water in the tube connecting the two bottles. What happens to he hydrostatic pressure at each point in the tube as you raise the first vessel by 30 cm?

5. Oct 31, 2013

### Hepic

So,If it this phenomeno is only about with tube,I can change waters via tube only(having the bottles at the same height?)?

That what I mean is,to leave the bottles in the same height,but to change the tube,and make it as it will be when I have one of bottles heigher. If I do that,water level will change??

6. Oct 31, 2013

### Staff: Mentor

No, that won't work either. Here's something that might help you visualize what's going: Imagine that there is a plug in the tube, so that water cannot flow between the two vessels to equalize the level. Now calculate the hydrostatic pressures on either side of the plug - if they're equal nothing will happen when the plug is removed and if they're not equal water will flow from the high pressure side to the low pressure side and the water levels will change. Try this for each of the cases that you've asked about so far in this thread.

7. Oct 31, 2013

### Hepic

My english is bad,so I undestood what you mean but not at all.
Can you explain me with physic rules,why when I put a bottle heigher his water goes to the less heigh bottle?
(The heigher has more hydrostatic pressure?)

8. Nov 1, 2013

### CWatters

See diagram.
The pressure at A and B are different (not the same).

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9. Nov 1, 2013

### Hepic

Yea,I understood that. The heigher will have more pressure because there is more water,but when we use bottles with cube and go higher the one bottle,water will be the same,will not be more???

10. Nov 1, 2013

### Staff: Mentor

When you raise the left-hand container, you are not raising the part of the tube that is connected to the right-hand container. Therefore, the water in that part is deeper after you've raised the container, so the hydrostatic pressure in that part of the tube is greater.

11. Nov 1, 2013

### CWatters

Sorry. I do not understand what you say. Can you make a drawing.

12. Nov 1, 2013

### Hepic

http://postimg.org/image/512frpz47/

Here is a photo. In number 1 I show the first situation,and in number 2 the second situation.
When you go from 1 to 2,you raise the bottle with the water,so the water is not deeper,but has more pressure??

13. Nov 3, 2013

### CWatters

Where does it have more pressure?

Please mark on the drawing where you are talking about. Bottom of the water?

The pipes are in the air above the water ??

14. Nov 3, 2013

### Hepic

I do not know what pressure there is. Can you explain me in what is the difference between 1 and 2,so water way changes?

15. Nov 4, 2013

### CWatters

Sorry we are still having problems communicating.

I don't understand your drawing. In 1 the pipe is not in the water. The end of the pipe is in the air. No water will flow.

16. Nov 4, 2013

### CWatters

In 2...

No water will flow. On the right... the pressure at the bottom of the pipe is higher. It is not high enough to raise the water above the surface.

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