Properties of a coke bottle and other magic

[alan2here]

I don't drink coke, but I should imagine they are quite sturdy. I wondered how a lot of this is done but specifically the coke bottle trick.

 

 

Is it plausible that is having so much strength against force from the outside a coke bottle is week against force from the inside? Much like how an alligator can bite closed with enormous force but can't resist the force of a stout rubber band holding it's mouth closed when attempting to apply opening force.

[big314mp]

It breaks because he put something very hard in there, like a sharp piece of ceramic. The fact that the ceramic is hard and sharp, means that when it hits the side of the coke bottle, it can create quite a bit of pressure at one specific point, cracking the bottle.

[Phi for All]

It breaks because he put something very hard in there, like a sharp piece of ceramic. The fact that the ceramic is hard and sharp, means that when it hits the side of the coke bottle, it can create quite a bit of pressure at one specific point, cracking the bottle.

I might agree if the magician was the one holding and shaking the bottle, but it was supposedly a random audience member. I agree with alan2here that it might have something to do with a bottle being more vulnerable from the inside.

 

There is some kind of liquid in the bottom of the bottle, not much but it's there if you watch closely as the bottle "pops". I'm guessing he put a chemical in the bottle just before handing the bottle to the woman, and the glass shard had another chemical on it which created an exothermic reaction when the woman shook it from side to side. The heat caused the thick glass to expand unevenly and Viola! the bottle's bottom breaks free with a slight popping sound. An endothermic reaction would possibly accomplish the same thing, but I think frost would have quickly formed under those hot lights and given it away.

 

Chemical reaction seems much more likely than any kind of percussive method, even if it attacks from inside the bottle.

[big314mp]

The reason I suggested the ceramic shard, was that a version of this is a very common parlor trick, and it is also a common way of breaking into cars:

 

http://en.wikipedia.org/wiki/Ninja_rocks

[Phi for All]

I'm calling in some chemical help: http://www.scienceforums.net/forum/showthread.php?t=35282

[big314mp]

If coke bottles are tempered, it would be a relatively straightforward explanation:

 

http://www.popsci.com/diy/article/2008-06/shattering-strongest-glass