's a video of someone removing a cork from a wine bottle using a shoe. The cork comes out of the bottle but I don't see how - although I'm not the world's greatest physicist, of course :-) IMHO the cork, if it moves at all, should go inside the bottle because (and this is the bit that justifies it being in a DIY group) it would seem to be the same principle as putting a hammer head on a shaft, ie, shaft and head travelling downwards, shaft stops, head carries on downwards and fits snugly on shaft. Wine bottle and cork travelling in same direction, bottle stops, cork should continue same way as the bottle, not go in the opposite direction - shouldn't it?
As he says it is the shock wave travelling through the wine that pushes out the cork. The cork does not have sufficient mass for your suggestion to move downwards to any degree. In the case of the hammer head, the head is much heavier so dominates over the shock travelling up the handle.
Not sure why he demonstrates this on a wall, I think I'll try the floor first.
Seems like the cork, being lighter, gets left behind somehow. We've got a couple of physics grads on here, so I'm sure an answer will soon be forthcoming.
GCSE physics. Newton's Laws. Every action has an equal and opposite reaction. Same reason newton's cradle works.
Bottle in shoe hits wall. Newton's second law tells us force=mass x acceleration. Wall doesn't move and exerts equal and opposite force on shoe. Shoe then exerts that force on bottle. Bottle then exerts that force on wine. Wine exerts that force on cork. Cork will then move out roughly the same distance that the base of the bottle sunk into the insole of the shoe.
I was shown this some time ago, but using a towel rather than a shoe. I rather think that I learnt about the technique from a Greek whilst on a company course. Possibly the only thing that I now remember from the course.
The hammer head analogy does not really fit since the cork has no significant mass. Even moving at high speed it would contain very little kinetic energy - certainly not enough to break the friction lock in the neck of the bottle.
It basically utilises a mass which is free to move, and a spring. In this case the mass is the wine, and the spring is the air gap. Rather like the pneumatic hammer action of a SDS drill[1]. The relatively gentle movement of the container (by a swash mechanism in the drill) is converted into a sharply released shock by converting its momentum into compression of an air spring, and then allowing the spring to release unrestricted. In the case of the drill; the spring accelerates a hammer, and in the bottle; it accelerates the wine.
In this demo. you accelerate the whole bottle, and then bring it to rest abruptly (the shoe adding enough protection to stop the bottle breaking on impact). As it comes to rest, the kinetic energy in the wine will cause the air gap at the top of the bottle to get compressed (and opening a low pressure rarefaction or cavitation adjacent to the cork). When this expands again, it forces a piston of wine back up the neck of the bottle at speed. This then dumps its significant momentum into the cork, pushing it out.
If you do it with the bottle upright, then you would not have created the required piston effect with weight adjacent to the cork, and an air gap in a suitable place to compress.
Surely the only way the air could get compressed is if the wine expands and I don't think this is likely to occur significantly.
It seems more likely that it's to do with rebounding shock waves within the bottle passing through an incompressible medium (the wine) and transfering some of the energy to a moveble object (the cork).
The "Constantinesco" bottle opener. Needs to be French wine. If you try it, you'll find that some bottle shapes (actually the bases) work, others don't. This suggests that it's an internal shock wave that's responsible, not just inertia.
Be warned: much modern wine is in lightweight bottles, and the bases on those can break when you hit them. Mind you, they're probably going to be screwtop anyway. It doesn't work on plastic corks either, as those are so tight a fit.
The air spring, combined with atmospheric pressure then slams the wine back up the neck of the bottle where it hits the cork. Even if the impact is not sufficient to cavitate at R, there will still be a large pressure drop followed by a shock wave.
Once could try an experiment by corking a full bottle with no air gap (would need some way of venting the air while corking), and hitting that. I expect the effect would be much reduced (atmospheric pressure and hydraulic lock would also make getting cork out difficult).
Not really my subject - never could handle the equations in physics - but it looks to me as if others have missed what might be the effect of the taper of the normal bottle shape. Like a stiletto heel concentrates body weight into a tremendous force on a small area, hitting the wider area at the bottom of the bottle, I would imagine results in the force being considerably magnified by the bottle taper by the time it hits the cork.
Problem of course, with this method, is that corks tend to be used on older wines that are likely to have sediment, so the last thing you want to do is hit the bottom on a wall. If it's a home stored wine and the bottle has been on its side so as to keep the cork moist, there will be a layer of sediment all down the side which will make a right old mess after any thumping. But on the other hand home brewing corks are usually rubbish and will not have been airtight anyway...
Good bottles have both the capacity and the safe pressure in mm moulded around the bottom. Go for 80mm and above (Anything that has had fizz in should be safe.) if you are reusing the bottles for home brew, and stick to screw caps, except on the odd bottle you want to make a show of.
The standard party method of dealing with lack of cork screws, was the wooden spoon handle or very strong finger method, to push the cork in rather than out. A tea spoon then holding the cork out of the way for the initial pouring. More stylish was the excellent 'corkette' in the pocket, 'just in case'. Shame that my one stopped pumping eventually, and they don't seem to make them any more: too dangerous I suppose.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.