An unexpected way to inflate a balloon - Numberphile

A weak paper crease is like a spring that wants to unfold

Paper is made out of fibers and when yuo crush paper you bend those fibers that were pressed to be straight. So there is some spring force to try to strayghten those fibers back to what was their original position. This force is not strong but strong enough to see a movement on ball of crushed paper just when you release it. Try the same with foil and you get no movement as there are no spring forces acting on getting it back to flat.

Anti-fragility?

who all wants a visit of Tadashi's bookshelf ?

Im never gonna blow any balloon again

The Answer to Brady's Question that Why does paper expands when crumbled ? Dr Tokieda has explained it in his toy's video, the answer is that the paper fibers at a small fundamental level have negative Poisson ratio !

"Fighting back"
I think regaining original shape would be a better term🤔

yo this is a perfect analogy for inflation in the global market

Who thinks Tadashi should play for National volleyball Team in Japan

I think what makes the over crumpled fighting back is the air from the other side.
It distributes it almost evenly.
Like if you have a different theory.

I like Tadashi and this unexpected "trick" but the explanation isnt very satisfactory.

Tadashi's voice grab my attention.
Salve from Brasil

Does that 'fighting back' happen because of Gaussian curvature in any way?

....But will it work in vacuum?

he explains it very well

what a chad

I can explain why it wants to partially inflate. Fold a piece of paper, but don't crease it all of the way. The paper wants to slightly open up, doesn't it? Now, the ball has a bunch of these "folds", so due to all of the folds, the ball wants to "open" up.

I wonder how much the heat from smacking it is contributing to the inflation.

The shape is coming back due to whats called restitution

Professor Tadashi is probably my favorite professor of all time! He really enjoys the maths as well as the explanations of them!

It's all due to material elasticity.
If it weren't paper, but a flaky material like pie crust, it wouldn't behave like that at all.
Engineering, kids.
Git gud.

I wonder how one could now calculate the approximate optimal force and shape of the impactor. Finding this could teach us the best technique for hitting the ball and inflating it in the shortest time possible.

I remember doing this trick myself a kid once with a paper balloon before. It just naturally wants to regain the sphere shape, and smacking it just helps it along, "sucking" some air back in along the way from the material itself wanting to go back to a form of less stress/reach "equilibrium" again ;)

I think the graph the professor drew is not perfectly correct, see when you hit the balloon the size does not drop. Yes, the balloon gets crumpled where the balloon is hit, yet it gets inflated from the opposite side, thus the size does not drop. At least this is what I think.

Can we get Professor Tokieda to do this video again but have him juggle the ball with his feet? (Math and football fan over here!)

Japanese Volleyball?

please more of Tadachi's toys!

the shape of the graphed curve, losing volume when hit but regaining more as it waits for next hit reminds me of that bitcoin things price when graphed on a chart over the long term. intresting video!

Fill it with butane and then.... You know.

This guy is why we need brexit.

We have to stop europeans like him from coming over and stealing our maths jobs, with smaller and more efficient salaries.

I wonder how much difference the grain direction of the paper affects amount of hits before inflation.

How do potters "tap to center"? This balloon hitting action reminds me of tapping randomly to make circular object on a spinning disk reach the center. (I am a potter and can recenter a piece with just several taps)

Japanese people are incredible.

I think it is all of these phenomenon that makes it happen
1. if the crumple is over a point/limit, it will revert back to make it less crumple, and air goes in.
2. if the crumple is not in the limit, it will stay at it's position.
3. if the paper balloon is hit very fast, air doesn't have enough time to escape from small hole.
The hole works kind of like a one way valve for the balloon if the conditions is met.

What about hitting the balloon while it is already spherical? You say that the ballon will never become a perfect sphere, but why? Based on this theory and given enough time, it would eventually become perfect. Of course, we know that this can't happen, which means that there is a point where you lose more than you gain. So at what moment does the impact from hitting the balloon result in more damage than can be repaired?

What a delightful man. Excellent and entertaining explanation.

His accent just comes straight out of southpark haha

Where can I get this sphere?

No kamifusen was hurt during this video!

okay, but why does it fight back?

hes using those martial arts reflexes to casually toss the ball around while explaining

If the shape is not a sphere per say cylindrical. Will the result be same ( cylindrical on inflation) ?

He does got some serious skiillllzzzz im sorry its not 2005

Hmm

Only Japanese discovered this because western people would have hit it so many times in a row