# What would happen if

If you had something like a balloon, and you filled it nearly full of water, then take it into space where there is no gravity? Then pump air bubbles into the balloon causing the balloon to stretch further.

How would the bubbles interact with each other? Would they join when they come near each other? Would they be attracted to each other?

Homework Helper
If you fill a balloon with water then the atmospheric pressure and pressure caused by tension in the balloon would equal the internal water pressure.

If you then take into space, the atmospheric pressure would drop to 0 and I suspect that the maximum possible tension in the balloon would not be enough to equal the internal water pressure- the balloon would burst.

I'm not sure what you are getting at- the bubbles experience (nearly) no bouyancy, but there is still pressure- tension in the wall of the balloon balanced by the internal pressure of the fluid(s).

When items containing fluids are launched (cooling systems, water handling, etc), they have to have overflow valves and controlled leak paths- but that's more due to changes in temperature than pressure (water is nearly incompressible).

vipulsilwal
i don't understand what Halls wrote...
when balloon was on Earth the most of pressure water was exerting was due to gravity of Earth ...
i guess in space water might take spherical shape in order to minimize the potential energy... and the bubbles will either stay at their location or they might join together at center of spherical water

Gold Member
Some clarification please. When you say 'take it into space', do you mean:
- in a space station, or
- in the vacuum of space?

HoI assumed you meant into the vacuum of space, but I'm not sure that's what you meant.

If you are simply talking about how bubbles behave in microgravity, they will not experience bouyancy, no, but if they do come near each other, tehy will coalesce into a larger bubble due to surface tension.

Ignea_unda
If you fill a balloon with water then the atmospheric pressure and pressure caused by tension in the balloon would equal the internal water pressure.

If you then take into space, the atmospheric pressure would drop to 0 and I suspect that the maximum possible tension in the balloon would not be enough to equal the internal water pressure- the balloon would burst.

Actually the balloon would most likely stay intact. Because water is a liquid there would be no expansion. Since there is no air in the balloon the atmospheric pressure would not matter.

As for the way the bubbles would interact, I'm not positive. I believe that they would group together, but I'm not positive if it would be against the side of the balloon or in the center.

vipulsilwal
will that be due to surface tension or just to minimize the gravitational potential water will displace bubbles and bring them to center and coalesce

Mentor
Guys, pay attention to what the OP actually said, a few of you added some wrinkles that the OP didn't say. The only ambiguity is, as Dave pointed out, whether the balloon is in a vacuum. The balloon just water initially, then water and air. So there are 2 cases, with two parts each:

Case 1: Balloon in pressurized spacecraft
When the balloon contains just water, it behaves much like a tossed/dropped water blloon on earth. When air is introduced, the air will coalesce into one bubble due to the surface tension of the water. As said above.

Case 2: Balloon in the vacuum of space
This is as Halls said, but keep in mind that the OP didn't say how much air is added. Regardless, it takes only a relatively small amount of atmospheric pressure air to be introduced into a balloon in a vacuum to make the balloon inflate a lot and pop. The balloon in a vacuum chamber is a common high school physics demonstration:

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Ignea_unda
That is a good point. I wasn't thinking about the adding of air when talking about the water and the surface tension. It makes sense that the balloon would pop if much air was added.

sorry, I meant in a space station, or something that was pressurized. I chose a balloon because I figured the more the balloon stretched as it was filled, the more compressed the air inside would be. Rather than thinking space, just think 0 g.

Would it be possible to get bubbles orbiting each other?

Would the air end up forming a "shell" around the water?

Gold Member
Would the air end up forming a "shell" around the water?
I doubt it. That would be the worst possible state. The water will act to minimize surface area between air and water. I believe the ideal shape would be a nearly spherical bubble that hugged the balloon wall.