Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: scientizscht on 18/03/2020 19:00:19

Title: Is it possible that an open tube has higher water surface than its container?
Post by: scientizscht on 18/03/2020 19:00:19

Hello

When we a tube with open ends half immersed into a huge water container and we pour water inside the tube, will the water in the tube rise above the water surface of the container?

It's puzzling that when you pour the water, there is extra pressure on that water column and how this extra pressure will be extinguished so that the total water level of the container will rise.

Any idea?

Title: Re: Is it possible that an open tube has higher water surface than its container?
Post by: Bored chemist on 18/03/2020 19:03:54

https://en.wikipedia.org/wiki/Capillary_action

Title: Re: Is it possible that an open tube has higher water surface than its container?
Post by: scientizscht on 18/03/2020 19:05:10

Quote from: Bored chemist on 18/03/2020 19:03:54

https://en.wikipedia.org/wiki/Capillary_action

I know but I am talking about large tube and huge water container and very long tube that reaches very high depth with lots of pressure.

Title: Re: Is it possible that an open tube has higher water surface than its container?
Post by: Bored chemist on 18/03/2020 19:32:11

You can get a long tube, put  a cork in the bottom, and put it in a tank of water.
Then fill it with water, then take the bung out.
For a short while you will have what you asked for.

Why bother?

Title: Re: Is it possible that an open tube has higher water surface than its container?
Post by: scientizscht on 18/03/2020 20:00:49

The tricky part of the question is this:

How can a single column of e.g. 1m of water exert pressure that will squeeze the water in the long tube towards its bottom opening which is located at large depth where the pressure is high.

If you pour water on the free water surface of the container, it's reasonable that it will spread out and increase the water level.

But if you pour it inside a tube with open ends that is immersed into the container, the water cannot spread out due to the tube walls so it will either have to stay lifted above the container's level or it will have to squeeze all the water down the tube and minimally increase the water level of the container.

The water you pour into the tube has a specific weight and exerts a specific pressure and it is a bit puzzling how that pressure can actually push down the whole water column of the whole length of the tube and lift minimally water level.

Title: Re: Is it possible that an open tube has higher water surface than its container?
Post by: evan_au on 18/03/2020 20:01:56

Here is a case where water actually spouts far above the top of the tube.
This soda fountain is used in volcanic lakes to remove excess dissolved carbon dioxide.

Start at 5 minutes:

https://en.wikipedia.org/wiki/Lake_Nyos#Degassing

Title: Re: Is it possible that an open tube has higher water surface than its container?
Post by: Bored chemist on 18/03/2020 20:16:56

Quote from: scientizscht on 18/03/2020 20:00:49

it is a bit puzzling how that pressure can actually push down the whole water column of the whole length of the tube and lift minimally water level.

Why is that a puzzle?