why does a coaster sometimes stick to the bottom of a glass
In: Chemistry
Suction.
The condensation or spilled liquid gets underneath and when the glass sits down, the weight pushes the glass down against the coaster. Air moves out of the way fast enough but liquids don’t always and if the liquid fills in all “the gaps”, it creates a vacuum. The air pressure surrounding the coaster/liquid/glass becomes stronger than the weight of the coaster… so it holds.
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