- #1
itsthemac
- 23
- 0
This might sound trivial, but I've always been curious as to why exactly when you put your finger on the top of a straw in a drink and lift it up, the liquid stays in it. We're studying pressure and fluids right now in my physics class, and I have a general idea that it has to do with the pressure of the outside air pushing up on the liquid in the straw. What I don't understand is exactly how to describe the whole thing. Shouldn't the pressure of the air in between the liquid and your finger be the same as it was before you put your finger on the straw? Does that pressure actually change at all just from enclosing it? And if it doesn't change, then wouldn't the same forces be acting on the liquid that were acting on it before you put your finger on it? thanks in advance