Last night we had dinner out on the porch. The boys chugged their milk almost immediately, so I went and got the bottle out of the fridge, replenished their glasses, and then put the plastic top back on but kept the milk out in case they wanted more.
Maybe fifteen, twenty minutes later all of a sudden the top popped right off and landed a foot away. So either we have a poltergeist or there’s physics (i.e. applied math) involved. There hasn’t been much other evidence of a poltergeist, so physics it is! And I’m thinking that since it was a warm and humid evening, it had to do with either the air inside the bottle warming up and expanding (or was the air already warm from after I poured the milk?) or the milk itself warming up and expanding. Anyone know?
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April 24, 2009 at 11:08 am |
I would be pretty confident that it was primarily due to the warming air expanding.
You can try a similar experiment with hot water. Put some hot or warm water in an empty container and close the lid, or just put your hand over the top sealing it. Then shake the container. The water evaporates quickly and builds up pressure. You might not even be able to keep your hand over the top without leaking pressure.