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Why does a balloon expand until the pressure of the gas inside balloon balances the pressure of the gas outside?
Wiki User
∙ 10y ago
In a closed container where air or other gases tend to occupy space, there is the presence of air pressure that does an upward force. This force exerted inside the balloon able the balloon to fly, but there is an opposing force outside it, which is also air pressures. Hence, the air pressure inside the balloon must be greater than the air pressure outside it, for the balloon to be lifted up.
I'm not sure this guy ^ answered your question or not. Actually, it's completely wrong. If you ARE talking about helium balloons, as he seemed to be, then Helium is a lighter gas than the combined gases in the air. Just like mixing olive oil and water, denser objects sink, and lighter objects float. Therefore, a helium balloon will float upwards until it pops.
If you WEREN'T talking about helium balloons, which I don't think you were, then you're like me. I've been doing some research to prove my theory. While hard to find, it seems to be pretty common knowledge in science (and yet, for some reason, my teacher was wrong about it - hence me doing outside research) that a balloon has a greater air pressure inside the wall than that outside.
Air pressure, technically, is a measurement of the amount of collisions against a surface at any time. In the case of balloon, it's supposed to measure how many particles at any in any given time space collide with the wall of the balloon and bounce off. However, since this is near impossible to measure, air pressure seems to be easier described as density. The similarity comes from the idea that when there are more molecules in the same space, more of them will be heading towards a collision course with the wall.
The first concept of air pressure within a balloon that you will need to know is that air pressures "try" to even out. With all the bouncing against the balloon wall (both in and out) there will be a certain amount of expansion/contraction. As air pressure itself is a description of the total forces against an object, each of these forces, on the outside of the balloon, causes the balloon to contract a tiny bit, while the inside forces cause the balloon to expand. With this knowledge, one would immediately assume the a balloon with high air pressure inside would expand based on the high amount of internal forces, and vice versa.
This would make the inside and outside air pressures equal.
However, the part I am looking for, that my science teacher doesn't agree with, is the fact that we are, after all, talking about balloons. Balloons have a certain elasticity to them that some won't take into account. When you stretch a balloon, you're filling it with potential energy. When you let it go, the potential energy is turned into kinetic energy and the balloon snaps back into its original position (though perhaps a little stretched out).
When you fill up a balloon with air, the balloon is being stretched. While the balloon is constantly releasing kinetic energy in an attempt to contract, it is also being pushed back out by the constant bouncing of the internal air molecules.
Because I'm still researching this, I'm not an expert, but basically, the internal air has to exert force not only to counteract the external air to keep the air pressures "even," but it also has to counteract the natural contraction of the balloon. Therefore, it requires more air pressure (more force) than the air outside the balloon wall.
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the gas pressure inside an inflated balloon always greater than the air pressure outside because as the atoms and molecules move about they hit the wall of the balloons which increases their speed so the gas pressure is higher then outside. The air pressure outside the wall is less because atoms and molecules can easily move about. When most of the atoms and molecules escape from the balloon the air becomes same outside and inside.
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Okay, no, that ^ just doesn't make any sense. Hitting the balloon wall does not increase speed. Also, the air outside the balloon is generally confined too. It is bouncing off the balloon, all of the objects in it's area, possibly walls and a ceiling...
And, according to your theory, if air is let out, what's left would still have a greater pressure, because it's still hitting the walls...not that this 'theory' makes any sense...
Wiki User
∙ 13y ago
Wiki User
∙ 10y agoThat's because the balloon is quite flexible. If there is a pressure difference, it will expand (or contract) as a reaction to that pressure difference.
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Why does a partially inflated balloon expand as it rises?
The pressure in the balloon stays the same, but the pressure outside drops as the altitude increases. And as the outside pressure drops, the balloon expands.
Why does a partially inflated weather balloon expand as it rises?
As height is gained the outside air pressure on the balloon is reduced. This reduction allows the gas inside the balloon to expand.
How does a balloon expand?
when you fill a balloon with air the air makes pressure. the air pressure maximizes the balloon fabric allowing the balloon to expand.
Why does the pressure outside the balloon decrease as it rises?
The pressure outside the balloon doesn't change when the balloon rises. By a balloon rising, I assume that air is being placed into the balloon. As the balloon fills with air, the pressure inside the balloon will increase. Since the balloon can stretch, the increasing pressure against its inner walls will cause it to rise, or more correctly put, expand. Eventually, the balloon will be stretched to its fullest capacity if more air is placed inside it. When it pops, the bang you hear is the high pressure of the atmosphere inside the balloon equalizing with the lower pressure of the atmosphere outside the balloon.
What causes the air pressure inside an inflated balloon?
The elastic contraction of the rubber in the balloon's membrane causes the pressure in the air inside an inflated balloon. When you inflate a balloon, you have to expand the latex of the balloon, which stretches when filled with air from a pressure of 760 mm Hg to as high as 840 (about 10% higher than standard atmospheric pressure). If you inflate a non-elastic mylar balloon, it takes no effort: the air inside is at the same pressure as the air outside.
Why does a partially inflated balloon expand as it rises?
The pressure in the balloon stays the same, but the pressure outside drops as the altitude increases. And as the outside pressure drops, the balloon expands.
Why does a partially inflated weather balloon expand as it rises?
As height is gained the outside air pressure on the balloon is reduced. This reduction allows the gas inside the balloon to expand.
How does a balloon expand?
when you fill a balloon with air the air makes pressure. the air pressure maximizes the balloon fabric allowing the balloon to expand.
Why does the pressure outside the balloon decrease as it rises?
The pressure outside the balloon doesn't change when the balloon rises. By a balloon rising, I assume that air is being placed into the balloon. As the balloon fills with air, the pressure inside the balloon will increase. Since the balloon can stretch, the increasing pressure against its inner walls will cause it to rise, or more correctly put, expand. Eventually, the balloon will be stretched to its fullest capacity if more air is placed inside it. When it pops, the bang you hear is the high pressure of the atmosphere inside the balloon equalizing with the lower pressure of the atmosphere outside the balloon.
What would happen if you put a balloon in the sun?
It would expand as the gases inside expand against the pressure of the skin of the balloon and the atmospheric pressure.
What will change the size of the weather balloon as it rises?
The pressure of the air inside it. The higher the balloon rises, the lower the outside air-pressure. With less pressure outside, the balloon expands because of the pressure of the air inside it. Eventually, the balloon bursts, and scientists recover the instruments when they fall to earth.
What makes the lungs operate?
its all by pressure, our diaphragm (muscle in our chest) contracts and relaxes causing high and low pressure and makes the lungs expand etc, think of a balloon in a jar and you can controll the pressure on the outside of the balloon, it will inflate and deflte
What happens to the shape of a helium balloon as it rises?
As the balloon rises, the air pressure outside will decrease, and the balloon skin will deform till the pressure on both sides of the skin is the same. Thus your balloon will inflate in shape, towards the spherical, which is the limiting shape for a simple balloon.
What causes the air pressure inside an inflated balloon?
The elastic contraction of the rubber in the balloon's membrane causes the pressure in the air inside an inflated balloon. When you inflate a balloon, you have to expand the latex of the balloon, which stretches when filled with air from a pressure of 760 mm Hg to as high as 840 (about 10% higher than standard atmospheric pressure). If you inflate a non-elastic mylar balloon, it takes no effort: the air inside is at the same pressure as the air outside.
How does air expand in closed objects?
cool Actually, when there is warm air, like in a balloon it will expand. When you go outside, the balloon will shrink if it is cold outside. When you go back into the warm indoors, the balloon will go back to its normal size.
Why does a sealed gas balloon expand when it is brought from ground level to the top of a mountain?
the air is less dense at altitude, therefore it exerts less pressure. the gas in a sealed balloon will exert the same pressure regardless of it's altitude, so, with less outside pressure to overcome, the balloon will expand.
A partially inflated balloon is released from the ground level and becomes larger as it rises in the atmosphere?
It is true that it will become larger as it risses in the atmosphere. This is because the pressure surrounding the balloon decreases, so the pressure inside the balloon wants to equalise with the outside pressure. This causes the balloon to expand as the inside air is trying to get out. That's why things get 'sucked out' of a plane if there if someone opens the door at 30,000 feet, the cabin pressure is trying to equalise by removing the objects and air inside it.
