How to open a winebottle with a shoe

spareine

Several youtube videos show how to open a winebottle with a shoe, if the corkscrew is missing. Normally I would have provided the link, but physicsforums does not allow me to do so. Please search in youtube for EHTADX5nxT8, or for [winebottle shoe].

My question is: what is the physics behind it?

Simon Bridge

Have a look here:
http://www.drvino.com/2010/07/16/how...tle-shoe-croc/

I've seen:

1) wine bottle accelerates towards the wall
2) the inertia of the wine makes it want to stay in the same place so it flows towards of the neck end of the bottle (air gap opens up between wine and bottom of bottle).
3) the wine and the bottle are at same speed
3) the bottle hits the wall and almost instantly stops
4) but the wine continues to flow forward (like someone in a car), hits the bottom of the bottle and rebounds, hits the cork and pushes it out a bit

... note: wine rebounds on the (compressed) air/gas-gap in #2, and CO₂ may come out of suspension with the agitation too. The shoe is to cushion the bottom of the bottle against breaking.

You want to keep the bottom higher than the top or the air gap may cushion the cork?

Seems reasonable.

haruspex

There may also be some pressure build up from the heat from all that banging. No way to treat a decent wine though.

Simon Bridge

There may well be but then it wouldn't matter how you bang it.
Also normal temp variations would likely be bigger than the heat from banging... though it can happen that wine in a bar spontaneously uncorks from heat, that would be gassy wines.

spareine

The proof of the pudding is in being able to calculate the force on the cork, F. This force should exceed the maximum friction, F_max, which is something like 200 N. F is presumably the same as when letting the bottle fall neck-down with a pvc-pipe around the neck of the bottle (the pipe serves to stop the bottle before the cork would hit the ground). That force is

F = m•Δv/Δt = Δv•(2/π)•√(m•k)

where m = ρ•A•h (ρ is the density of water, A the cross sectional area of the cork, h the height of the fluid column pushing against the cork),
Δv is equal to the velocity of the bottle just before impact,
Δt is the deceleration time due to the cushion at the target, Δt = (π/2)•√(m/k)
k = spring constant of the cushion.

The volume of the air bubble does not appear in the formula. Apparently that volume does not matter for the onset of cork motion. Nor does the shape of the bottle matter.

Right?

Borek

When I was young we did it hitting bottom of the bottle with the hand.

Q_Goest

I was sitting in a chair once with an open bottle of beer in my hand which I carelessly dropped. The bottle dropped about 1 foot straight down and landed standing up. When it did, it shot a squirt of beer that hit the ceiling, 8 feet high! It could be that it has to do with the beer being carbonated or perhaps there's some focusing of energy that can be attributed to the shape of the bottle. If it is due to a focusing of energy, it could be that some wine bottles can be opened this way and others can't.

AlephZero

I would think that was because the shock wave travelling through the fluid after the impact with the floor (or more specifically, the negative pressure wave behind the shock wave) caused the dissolved gas to come out of solution, and the liquid above the released gas had only one place to go to get out of the way - upwards.

haruspex

I don't think you can assume it's the same. The way the fluid returns to the cork end may be greatly influenced by both the air space and the shape of the bottle, particularly the punted base and the narrowing toward the neck.

spareine

Ah, this list is from a topic in the Naked Science Forum, may be you meant that link:
http://www.thenakedscientists.com/fo...?topic=36694.0

In reply #17 of that topic the Naked Scientists present an interesting high speed recording, zoomed in onto the neck of the bottle. They observed that large short-lived cavitation bubbles and small long-lived gas bubbles appear when the bottle hits the wall. The large bubbles collapse rapidly, within a single time interval of the camera (600 fps). The Naked Scientists assume the force on the cork due to the collapse of the bubbles pushes the cork out of the bottle.

(Although to me it is not evident why the force on the cork during the creation of the bubbles is smaller than the force during their collapse, as required for a net displacement of the cork).

Simon Bridge

The gas compresses but the liquid doesn't.

Here's the link:
http://www.thenakedscientists.com/fo...?topic=36694.0
... thanks. You should find that PF will let you post links after a few posts.

spareine

Which gas compresses? The air bubble in a new wine bottle is about 4 to 8 cm³, depending on the bottle. The volume compression of the air bubble during the collision is insignificant because the liquid is incompressible. The pressure in the air bubble hardly changes.

Simon Bridge

I meant " in general".
How did you track the compression of the bubble?

superedwin

Interesting topic..I'll try later

laddhoffman

Sounds to me basically a case of impulse. Bottle collides with tree; fluid inside rebounds more than glass does, since it is more elastic; rebounding fluid collides with cork, pushing it out. The collision with the tree is not very inelastic, and that kinetic energy has to go somewhere: the cork is the only thing free to move, to dissipate energy, except the sole of the shoe / the tree / your hand, so those things just have to be strong relative to the frictional force of the cork in the bottle. Specific fluid mechanics inside the bottle are relevant, but as I see it that's the basic overall picture.