Is buoyancy possible without gravity?

In summary, the concept of buoyancy is based on differences in density and pressure, and can occur in the absence of gravity. However, in a planet-sized sphere of water, gravity may play a significant role in the buoyant force. Additionally, in a rotating system, pressure gradients can also create a buoyant effect. Overall, buoyancy can be observed in various scenarios, both on Earth and in space.
  • #1
scientifico
181
0
Hello, does bouyancy exist if there isn't the force of gravity but i push down the object in the water with my force?

thanks!
 
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  • #2
The buoyant force on an object is due to the pressure of the fluid on the object. But without gravity there would be no pressure and thus no buoyant force.

Does that address your question?
 
  • #3
Doc Al said:
The buoyant force on an object is due to the pressure of the fluid on the object. But without gravity there would be no pressure and thus no buoyant force.

Does that address your question?

I thought that, say, a gallon of water(in the form of a sphere, for example)in deep space does not spontaneously separate into H2O molecules; rather that the "sphere" is maintained.

As such, a bubble within that water sphere would experience pressure; forcing the bubble to the exterior.

Could be totally wrong though...
 
  • #4
scientifico said:
Hello, does bouyancy exist if there isn't the force of gravity but i push down the object in the water with my force?

thanks!

The origin of "bouyancy" is from differences in density; gravity is usually the relevant force but any force will do, for example the centripetal force.

So, bouyant flow can occur in the absence of gravity; for example, you can separate air from water in space by rotating the container- the air will migrate to the center.
 
  • #5
Andy Resnick said:
The origin of "bouyancy" is from differences in density; gravity is usually the relevant force but any force will do, for example the centripetal force.
Good point! (Although I'd say differences in pressure give rise to buoyancy, but a rotating system can certainly create a pressure gradient.)
 
  • #6
pallidin said:
I thought that, say, a gallon of water(in the form of a sphere, for example)in deep space does not spontaneously separate into H2O molecules; rather that the "sphere" is maintained.

As such, a bubble within that water sphere would experience pressure; forcing the bubble to the exterior.

Could be totally wrong though...
Sure, there'd be some small force.
 
  • #7
pallidin said:
As such, a bubble within that water sphere would experience pressure; forcing the bubble to the exterior.

That does not exactly appear to be happening here:

Waves, Bubbles and Reactions in a Free Sphere of Water


Ep.14 Antacid tablet reacting in a water sphere in space
 
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  • #8
This is a great point, there should always be a buoyancy effect; on earth, buoyancy is a consequence of Archimedes principle, it is clearly observable due to Earth's great mass and therefore formidable local gravitation field. However, a globular formation of water in space will still have a buoyancy effect provided by reaction due to the localized gravitational pull between each water molecule and also the energy in hydrogen bonds.
 
  • #9
Andy Resnick said:
..., you can separate air from water in space by rotating the container- the air will migrate to the center.

Good point;
Can also do it on earth... called a centrifuge...high g's separate more quickly ...even radioisotopes ...(luckily, Iran has yet to figure out how to perfect it. ;)) ..Or was it stuxnet that tripped them up?) ;)) he, he.


...
 
  • #10
Doc Al said:
Good point! (Although I'd say differences in pressure give rise to buoyancy, but a rotating system can certainly create a pressure gradient.)

I agree- since density is a continuum concept, pressure (or stress) is more appropriate than 'force'.
 
  • #11
pallidin said:
I thought that, say, a gallon of water(in the form of a sphere, for example)in deep space does not spontaneously separate into H2O molecules; rather that the "sphere" is maintained.

As such, a bubble within that water sphere would experience pressure; forcing the bubble to the exterior.

Could be totally wrong though...
Of course, the reason the sphere does not separate and bubbles "rise" to the exterior, is because of the gravitational force between molecules of water so this doesn't really fit your "no gravity" requirement.
 
  • #12
HallsofIvy said:
Of course, the reason the sphere does not separate and bubbles "rise" to the exterior, is because of the gravitational force between molecules of water so this doesn't really fit your "no gravity" requirement.

I think the OP is positioning his question with regards to external gravitational influence.
OP(Scientifico): Can you clarify?
 
  • #13
HallsofIvy said:
Of course, the reason the sphere does not separate and bubbles "rise" to the exterior, is because of the gravitational force between molecules of water so this doesn't really fit your "no gravity" requirement.

Umm ... perhaps not ... the intermolecular forces, such as hydrogen bonding, between the water molecules are many many orders of magnitude greater than the gravitational force. I suppose that in the case of a planet-sized sphere of water, gravitation might be a significant factor, but I don't really think that was what was being discussed in this example.
 
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1. How does buoyancy work in the absence of gravity?

Buoyancy is a force caused by the displacement of fluid, which is a result of the difference in density between an object and the fluid it is immersed in. In the absence of gravity, the force of buoyancy is still present but the direction of the force is not determined by the downward pull of gravity.

2. Can objects float in a zero gravity environment?

Yes, objects can still float in a zero gravity environment due to the force of buoyancy. As long as the object is less dense than the fluid it is in, it will experience an upward force and appear to be floating.

3. Is the concept of buoyancy still relevant in space?

Yes, the concept of buoyancy is still relevant in space. Although there is no gravity, objects in space are still surrounded by fluid, such as air or water, and will experience a force of buoyancy based on their density.

4. How does buoyancy affect the movement of objects in a zero gravity environment?

Buoyancy can affect the movement of objects in a zero gravity environment by causing them to appear to float or move in different directions. The direction of the buoyant force is based on the relative densities of the object and the fluid it is in.

5. Can buoyancy be used in space exploration?

Yes, buoyancy can be used in space exploration. For example, astronauts use buoyancy to move around in space during spacewalks by using their suits as a buoyant force against the vacuum of space. Buoyancy can also be used to propel spacecraft through the use of buoyancy engines.

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