Two Balloon Surprise

It seems that really the outside airpressure on the small balloon with its small volume is relatively bigger than the same outside airpressure is on the large volume other balloon. And that difference in relative pressure even overcomes the elasticy of the rubber of the inflated balloon.

:?:

How could that be? The bigger balloon has more square inches of surface, so wouldn't it have more air pressure both inside and outside?

http://physics.uwstout.edu/deptpages/physqz/balloon.htm

Interestingly counter-intuitive effect, horribly let down by the unhelpful explanation though.

When you inflate a balloon the first few breaths are really hard (your ears may even pop) but then it gets a lot easier easier. The thick rubber of the small balloon exerts much more force on its contents than the thin rubber of the large balloon. (A used balloon is easier to inflate than a new one.)

So when you equalise the two balloon system there is not enough pressure to keep the small un-stretched one inflated.

A much better explanation is here: http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/balloons-on-a-tube/

It is probably because at the start when your blowing up a balloon a small amout, it hasnt passed its plastic(perminant) deformation point so it will try to return to its original shape, the larger balloon is past that point so it cannot return to its original shape and is permanently deformed, therefore there is less pressure on the inside of the larger balloon..

Wow, y'all are smart! What's the OP?

To put it more simply - The small balloon is smaller, it doesn't just look smaller because it has less air in it. The air in it is under greater pressure than the air in the big balloon, so it squirts into the big balloon.

The concept here is compliance - how much or little resistance there is to inflation. As the other commenters have noted, uninflated balloons are much less compliant than inflated ones (although compliance drops again when balloons are completely inflated, so the experiment would have turned out differently with balloons that were fully inflated vs. half - inflated.)
This is a big deal in the physiology of the lung, where you want all the alveoli to expand equally. Surface tension decreases the compliance of small (uninflated or partiallly-inflated) alveoli, so they would tend to stay uninflated while inflated alveoli expand further. Surfactant works by reducing surface tension and increasing the compliance of small alveoli.
Cool demonstration, but the explanation was lousy.

Dammit Man! This just made me miss Mr. Wizard in a terrible way.

hahaha, you're right, that's the most confusing explanation ever!

Since everyone has already done a great job of re-explaining the tenants of compliance, I will take a moment to point out that when the scientist gets excited, he starts sounding like Harry Carey from SNL?

"If the moon was made of barbecue spare ribs would you eat it? I know I would. I'd wash it down with a nice cold budweiser?"

Sadly, the whole thing was spoiled for me by the presenter's "Eck-scapes".

Well, air pressure was stated as being 14.7 lbs/sq.inch.
Wonder if you mulitplied that by the surface area of the smaller balloon, as well as the surface area of larger balloon and compared the two, would one value be larger than the other?

One simple way to look at it is to make an analogy with levers.

When the balloon has a volume of, say, 10cc, adding 1cc to it is a large proportionate increase. This is like having to push a short lever hard. You don't have to put much air in to double the surface area of any bit of rubber - so to do that amount of work you have to push hard, but with a small volume.

When the balloon has a volume of 100cc, adding 1cc only has a small effect on the overall surface area of the balloon - the amount you have to stretch the balloon is tiny - like moving a long lever - it's easier but you have to do it for longer to achieve the same effect. You have to push more air in to double the area of any bit of rubber, but it's proportionately easier.

The explanation in the video is a little stupid, but has to be dumbed down so that children can understand. The kiddies will understand when they grow up. :)

If they had to dumb down the explanation, why bother even explaining it? Or is this just a science experiment they thought of because all the good ones were filmed already?

I bet they replaced the kid after that experiment. Totally blew the surprise.

I think Ethan's seen this trick before.

smaller balloon isnt Stretched out,
The tightness of the latex on the smaller surface as well as air pressure, will force the all with greater force.
Its the same as when you loose a balloon, Listen to it..As the last bit of air is being released, you hear a strange sound. and it JETS in 1 final Spurt.

OP = original poster Miss, sorta like OG but not

Ignore the air pressure, and imagine cutting the two balloons into a series of rubber bands- some from the very stretched-out balloon, and some from the barely stretched balloon.

Which bands are stronger? The stretched bands would be rather floppy compared to the others, just like a deflated balloon is floppier than a new balloon.

Now, imagine a pair of plastic bags about 1/2 filled with air and connected with the tubing. Put the stretched bands around one bag, and the unstretched around the other bag and what would happen? Exactly- the stronger, unstretched bands would squish everything over to the other side- just like we saw in the video!

Here's how I see it: The surface area of a sphere is given by 4(pi)r^2 whereas the volume is given by (4/3)(pi)r^3. Therefore, as the balloon gets bigger, the volume increases FASTER than the surface area by a factor of r. Since the rate at which air enters the balloon is constant, there is more and more room for air, so the density will DECREASE. So the smaller the balloon, the higher the density of air.

Hope this helps!

Mr. Wizard did explain this on one of his shows many years ago

It's nothing to do with the balloon itself, and everything to do with internal (not external) pressures. You can observe the same effect with soap bubbles.

Small balloon has higher pressure than larger balloon, therefore air is forced into larger balloon. What's hard to understand about that?

big balloon=more space (less dense)
vs.
little balloon=less space (more dense)

obviously the air would escape from a more dense container to a less dense one to balance out.

I'm not a scientist but I certainly hope this explanation make more sense :)