So today i noticed a little hole in the cap of my coffee mug.
If you cover that hole, the coffee does not flow, although there is nothing holding it back.
That is, because there is something invisible called air that is pressing it back into the cup, if it can not get other air through that little hole from outside?
Which is something that constantly confuses me (or my brain), because there is nothing there.
What would be a good illustration or an imagination, how all those pressure from around us works?
In: Physics
That little hole in the coffee mug allows air in which is required when you pour coffee out of the mug. Without letting air in, you’re creating a vacuum which locks in the coffee and prevents it from free flowing out.
The same thing happens when you block the top of a straw that is half submerged in a cup of water and lift the straw. The vacuum created at the top of the straw by your lip or finger prevents the water from dripping out of the straw.
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