I hate you so much right now. Also I think it's 5

None. The water is not running.

5

Also, you suck.

Unless I completely misunderstand how this works, I think 5 is the only one that will fill up. It then overflows, preventing any of the taller ones from filling. 7 is shallower but won't start filling until 3 gets fuller than 5, which it never will. This would be true whether the blockage between 2 and 3 is a mistake or not.

1 fills up first. the spigot is much winder than the tube so the glass will fill faster than it can drain.

Also rule

5

Wait... Fuck!

5, but it also depends on the circumstances. What liquid is used, temperature, viscosity, etc. There's some material science stuff that's far beyond the intended scope of this question.

I actually started to figure out the sequence...then I realized...fuck you, take my up vote

All of them are already full of air.

:.|:;

OH İTS THE FUCKİNG LOSS COMİC

1. 5 which begins to overflow into the room
2. 7
3. 4 and 6
4. 2 and 3
5. 1

This is assuming this is a cross section of something 3d and not something 2d otherwise air packets would get trapped and prevent some of this.

I'd recognise that pattern anywhere, but I focused in on the problem and almost didn't notice your dasterdly deed

Depends on how much you turn on the tap. If you fürn it up completely its 1,else its 5.

i hate you.

edit: read replies before telling me that 7 is walled off

but ignoring my loss, if everything is pressurized i think 7 if unpressurized i think 5

They are all full already, of air.

All I know is, 7 is leaking out.

There's only one "one" in the diagram, so I'm gonna say the one marked "1." Pretty easy.

Wouldn't scale and viscosity play a role? Seriously, imagine a river vs a capillary tube. Also how many dimensions? And forces involved? Is that a blockage between 2 and 3? Are the walls breakable? How will the fluid hold air? Are the lines into structure 5 lower than the walls? Is this in a vacuum?