system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it impossible to suck through a straw that's 10.4 meters long?

i understand that when it's too low pressure it starts boiling but what are the numbers as to what gets the 10.3 meters limit, is there any way to increase it through a 0 degree surrounding and a super thin straw? how did they calculate that limit? what are the formulas used?
gpt
The action of sucking does not actually pull on water. Rather, it allows the air on the other end to push by removing the air from the end inside of your mouth.

This means that, since there is only 1 atm of air, you're limited to that much pushing.

As water climbs the tube, gravity pulls it down, generating a pressure to counteract the pushing. This pressure depends solely on the density of water and the height at the top of the water.

So, solving for the density of water, we see that water can only get 10.4 meters above its surface from the action of atmospheric pressure. If the straw goes deeper than the water's surface, then the straw itself can be longer, but the water can only be raised above its surface by that amount.

The formula for hydrostatic pressure is quite straightforward. p = ρ g h

This is the pressure generated by gravity acting on the water, and it is the pressure that counteracts the pressure of air pushing up. Interestingly, the pressure of the air itself can be found using the same formula (although to get an accurate answer you have to modify it with calculus to account for gravity and changes in density).