Physics Question #2963

Chris, a 19 year old male from J-town asks on October 2, 2005,

A friend at a party showed me that you can take a glass bottle, fill it with water, but not all the way, leave the neck of the bottle empty, screw the cap on tightly, hold the neck with one hand, and hit the cap with your other hand in a fist (like a hammer), and suddenly the bottom on the bottle just breaks off and falls, almost like it just pops off of the bottle. I found this quite interesting and did it a couple of times. Once with an Arizona iced tea bottle and once with a rather tall and skinny Bacardi bottle. It worked on both. It has to be glass, have a neck and have a cap that screws on tight. How is this possible?

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The answer

Barry Shell answered on October 7, 2005

You can find a short explanation on the hyperphysics website.  Basically, you set up a pressure wave that creates an accelerating and collapsing vacuum at the bottom of the bottle where a weak seam exists in the glass.


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