If you let a helium balloon go in zero gravity, what would happen?
Would the balloon fall, rise, or pop??
Just something I have always wondered!;j
If it’s just zero gravity, the baloon would do nothing. Just sit there.
Now, if it were in a vacuum, the balloon might pop. Ur depends.
Have to assume a few other conditions but it will probably do nothing. It could very possibly pop if it was inflated in an earth atmosphere then placed in a vacuum but that has nothing directly to do with being in zero G.
If you want do some real world experiments along those lines let a helium balloon loose in a big car or van where it an move about. Whatch what happens when yopu accelerate, deccelerate or turn corners. You will probably see its behavior as non-intuuitive.
If it’s in someplace with air (a space station, for arguments’ sake), wouldn’t it rise? Helium rises because it’s less dense than air, so shouldn’t it still do so in zero Gs?
“Up” and “down” are defined by the way gravity pulls us. There is by definition no up or down in a zero-G or microgravity situation. Which way does a balloon rise when there is no up or down?
Marley, the buoyant force will equal the weight of the fluid displaced, giving a net force of the weight of the fluid displaced minus the weight of the fluid that’s doing the displacing.
In zero gravity context, the fluid displaced has zero weight, and therefore the balloon will have no net force and will not accelerate.
If this seems counterintuitive, imagine this, which is pretty much the only reasonable scenario that what’s being asked can be discussed.
- In the dead of space, there is a pressurized container containing nitrogen (air)
- Somewhere in the middle of the container a helium balloon is placed.
You should notice two things immediately. 1, it’s not clear which type of fundamental force could be giving a significant net force to the balloon and 2- if there is a force- an imaginary zero gr
avity buoyant force, what direction is it in? We’re in a weightless enviornment, there’s nothing to define what ‘up’ is. Where do you propose the balloon will go?
Which way is “up” in zero-G? A helium balloon rises because the heavier air is pulled down by gravity and the balloon is forced up by the air pressure under it.
Where are my manners? Welcome to SDMB CGoodall. I hope you enjoy the company on the board and that you decide to stick around.
Nah. Think about it. Which way would it prefer to go on the space station?
On earth the air nearer the ground is more dense than air farther up because garvity is pulling all the air down. The helium balloon is lighter than the surrounding air so the air essentially fills in under the ballon thus pushing it up.
On your space station air pressure is equal in all directions as there is no gravity to cause it to pile up and become more dense in one area than another. In practice there are bound to be minor differences and the air circulating and what not which would likely move the balloon around but in no predictable fashion. In a perfect zero-g with prefectly still air and no outside influences on the balloon it would stay right where it was left.
It can be very interesting to try this, or to ask people to predict what will happen. The principle is reasonably simple: the balloon seeks the lowest-density place it can find. This means it moves inside a turn, forward when you accelerate and back when you brake. But not many people guess that without thinking about it rather carefully.
And fire in zero-G…same thing but a little different mental picture.