B Does water pressure decrease in zero gravity?

[allister109]

me and my friend were talking on facebook and we couldn't think of an answer to the question, would water pressure decrease in zero G, you can see how far along we got before getting stuck in the picture belowhttps://www.physicsforums.com/attachments/105576

 

[Orodruin]

Your question is not really well defined. You need to specify the pressure of the surroundings and exactly what setup you are considering. If you pressurize the container, the pressure will be homogeneous throughout the liquid and equal to whatever pressure you put.

 

[Bandersnatch]

So, we're the 'physics nerd forum'?

 

[Khashishi]

Yes, it will decrease, all other things equal. You won't have the weight of the water contributing to the pressure. The water can still be pressurized by the container, but you also have that contribution with gravity.

 

[Chronos]

There is no hyrostatic force in zero g, just like there is no bouyancy in zero g. A container full of water would float around like an astronaut on the ISS. There could be some nominal force due to surface tension and intermolecular adhesion of water but it would be negligible. The water would still have mass hence inertial resistance to motion, but, no pressure - unless you somehow apply compressive force to the water inside the cotainer. The pressure you would feel diving on Earth would be absent because there is no gravity to provide column pressure.

 

[Nugatory]

So, we're the 'physics nerd forum'?

Yes, and proud of it too!

 

[Khashishi]

Of course, with no pressure, the water will boil. If it is in a leakproof container like a spaceship, the water pressure will equal the air pressure.

 

[newjerseyrunner]

Pressure = Force / Area. Put 0 in for force. :P. There would be negligible electromagnetic interactions as well as even more negligible gravity but for the most part if there was no other interactions, it'd just sit there slowly increasing in entropy with quantum fluctuations.

 

[person_random_normal]

In zero g weight of water is zero so
Zero pressure

 

[Chuck Keranen]

So as I understand it, the atmospheric pressure surrounding a quantity of water will give it its globe shape. If that water is suddenly placed in a vacuum, such as space, it boils off?? Becoming what? Water vapor, or splitting into hydrogen and oxygen?

 

[jbriggs444]

So as I understand it, the atmospheric pressure surrounding a quantity of water will give it its globe shape.

Suppose that you have an arbitrarily shaped blob of water. Does the volume of that blob decrease if you mold it into a sphere shape? If not, why would you expect atmospheric pressure to do anything to alter the shape?

Try Googling for "surface tension".

 

[Khashishi]

Becoming what? Water vapor, or splitting into hydrogen and oxygen?

Water vapor

 

[newjerseyrunner]

Becoming what? Water vapor, or splitting into hydrogen and oxygen?

Vapor. The molecules are held together by pressure, the atoms making the molecules are bound together and will not just drift apart.

 

[Chuck Keranen]

Vapor. The molecules are held together by pressure, the atoms making the molecules are bound together and will not just drift apart.

Thank you...