The hole in my teacup.

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Estudios
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The hole in my teacup.

Postby Estudios » Thu Oct 03, 2013 5:50 pm UTC

Yesterday evening I took a bottle of white wine from my freezer where it had been chilling for around 25-35 minutes.

The cork was sticking. After applying force the wine bottle exploded (or possibly imploded) destroying the base.

While clearing up the pieces, I noticed some odd white bits in a nearby teacup. I looked at it more intently and discovered that what looked like a scratch on the side, was actually a 2mm wide, irregularly shaped hole, which pierced all the way through the cup, widening as it passed through to the central cup area, where tea is put.

after thoroughly checking myself all over for signs of bleeding, I decided to ask some people about what kind of velocity, shape and mass a piece of glass would have to have in order to create such an effect.

i can email photos of the objects on request.

Yours, amazed.

Elliott.

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LucasBrown
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Re: The hole in my teacup.

Postby LucasBrown » Fri Oct 04, 2013 12:11 am UTC

My knee-jerk reaction would have to be "astonishingly fast", but this depends quite a lot on the specific kind of glass and ceramic used for the bottle and cup. Pictures of everything from all angles would also be quite helpful.

Also helpful: how far away did the shards of glass tend to land? How far away was the farthest?

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Estudios
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Re: The hole in my teacup.

Postby Estudios » Fri Oct 04, 2013 12:28 am UTC

Sorry for the delay,

no need to email.

I have worked out how to post images.

will upload diagram (to scale) with dimensions later this morning
Attachments
image.jpg
damage to cup, from inside.
image.jpg
view of hole from outside of cup
image.jpg
damage to bottle
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billy joule
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Re: The hole in my teacup.

Postby billy joule » Fri Oct 04, 2013 12:56 am UTC

Estudios wrote: I decided to ask some people about what kind of velocity, shape and mass a piece of glass would have to have in order to create such an effect.



Brittle fracture is almost wholly dependent on defects and is notoriously hard to predict in real (defect ridden) materials. Unless you have some info on the crystallographic defects, residual stresses, surface flaws etc etc you'll be shooting spherical chickens at flawless crystals.

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LucasBrown
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Re: The hole in my teacup.

Postby LucasBrown » Fri Oct 04, 2013 1:58 am UTC

I'm going to downgrade my guess from "astonishingly fast" to 100 MPH or so, and the shard of glass responsible for the hole was probably a narrow sliver that hit the cup point-first. The "exit wound" is quite a bit larger than the "entrance wound"; this is along the lines of what to expect of a slow-moving impactor. In general, the faster an impactor is moving in a situation like this, the narrower the cone cleaved from the impactee in the collision.

The shard of glass was almost certianly pulverized by the collision.

Please not that this is only slightly more informed than wild mass guessing. As billy joule said, these things are vastly dependent on defects and grain structure in the materials involved. The behavior of materials with tiny grains such as metals are quite easy to predict when the items involved are the size we're dealing with here. Materials like the ceramic of your teacup have grains much closer to the size of the impactor and are vastly harder to predict without a detailed knowledge of structures of the individual grains affected by the collision.

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Estudios
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Re: The hole in my teacup.

Postby Estudios » Fri Oct 04, 2013 3:56 am UTC

I agree that the variables involved in examining the cup are simply too numerous: the age of the cup; its handling/wear and tear; wherher or not it had been recently used are all factors, and that's not even mentioning the fact that it is as you mentioned a flawed, granular material with a highly non uniform surface, (the pattern is embossed). The fact that I since threw it out, further compounds the issue.

There is also the possibility that it was not actually penetrated by the glass, but simply knocked hard in a spot, where it was likely to free the missing material.

That being said, I have focused on first trying to work out a rough upper bound for the potential velocity of exploding cold wine bottles, which have just been removed from the freezer. However, I'm having difficulty arranging the variables.

-edit it is worth noting that there was no noticable ice in the wine, which was expelled from the bottle, although the glass may have already reached sub-zero (c) tempratures. My best guess is that the wine was close to minus five or six c, the rough freezing point of a solution of nine parts water, one part ethanol.
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Tass
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Re: The hole in my teacup.

Postby Tass » Fri Oct 04, 2013 8:21 am UTC

I don't think the shard necessarily went through. With the right defects and stresses in the cup it could break like that from a relatively soft impact where the impactor bounced back. It was probably and insanely (un)lucky hit.

I don't think you could fire small impactors at cups at any speed to reliably make such a hole. Any speed high enough to penetrate would be likely to shatter the brittle cup.

webgiant
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Re: The hole in my teacup.

Postby webgiant » Fri Oct 04, 2013 11:25 pm UTC

Estudios wrote:I agree that the variables involved in examining the cup are simply too numerous: the age of the cup; its handling/wear and tear; wherher or not it had been recently used are all factors, and that's not even mentioning the fact that it is as you mentioned a flawed, granular material with a highly non uniform surface, (the pattern is embossed). The fact that I since threw it out, further compounds the issue.

There is also the possibility that it was not actually penetrated by the glass, but simply knocked hard in a spot, where it was likely to free the missing material.

That being said, I have focused on first trying to work out a rough upper bound for the potential velocity of exploding cold wine bottles, which have just been removed from the freezer. However, I'm having difficulty arranging the variables.

-edit it is worth noting that there was no noticable ice in the wine, which was expelled from the bottle, although the glass may have already reached sub-zero (c) tempratures. My best guess is that the wine was close to minus five or six c, the rough freezing point of a solution of nine parts water, one part ethanol.

While I'm finding the discussion of complex physics most enjoyable, the skeptic in me has to point out that I have not been told yet that perfect experimental conditions were maintained throughout the event.

Or, more specifically, I have received no information indicating that the teacup was observed not to be broken prior to the explosion of the wine bottle. While there is certainly a wealth of circumstantial evidence, there remains the possibility that a teacup was damaged in some other fashion prior to the explosion of the wine bottle, and that the explosion of the wine bottle was merely the event that caused you to notice the hole in the teacup, as opposed to the event that put the hole in the teacup.

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Estudios
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Re: The hole in my teacup.

Postby Estudios » Sat Oct 05, 2013 2:44 am UTC

I had actually considered that the tea cup was injured prior to the bottle exploding event. As you say, I did not carefully inspect the undamaged cup before the explosion. but several points cause me to reject this conclusion.

-My mother in-law is staying with us and she compulsively cleans everything, resting only at night. She would have noticed it first.

-There were fresh bits of broken ceramics in the cup, indicating it could not have been broken more than about 20 minutes prior to the bottle event, which was her last visit to the kitchen.

-There was a small quantity of water in the cup, which whilst may have been left there from rinsing, was of a sufficient quantity to suggest that someone had drunk from the cup shortly prior to it's breakage.

-It is unlikely that the damage was caused by a regular dropping incident because dropping cups breaks them differently, in my experience.

The alternatives to the bottle explosion being the cause of the damage therefore are:

1)Someone drank from the cup without noticing the hole or the bits at the bottom of the glass and left it there.

2)Someone, knowing that a bottle exploding type event was likely to occur within twenty minutes time, filled the cup with a small quantity of water and then (quietly) chisled a hole in it in order to fool me.

In any event something scientifically interesting, or possibly psycologically interesting had to have happened in order to damage the glass without making it fall from the kitchen surface.

It is infact this mystery, which makes me want to know whether an explosion caused by a sudden pressure change in a wine bottle could have caused the damage. In either case as a sceptic myself, I shall treat my mother-in-law with due suspicion until I discover the true cause.
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