Why does the water stay in?

[elgroucho]

If I put some water in a bottle, and it has one of those nozzles on it like the bottled water you buy in the shops, and i turn it upside down why doesn't all the water pour out? You usually get a couple of dropsbut that's it. What is going on?

[maelogman]

If a little water escapes, the pressure of air above it, inside the bottle, drops, The pressure of air outside is greater and keeps the rest of the water in. The nozzle is too small to allow air to get in at the same time as water comes out, to equalise the pressures

[Gef]

Because the top is closed.

[fo3nix]

I like Gef's answer ;)

But yes, it's all down to pressure with these kinds of things. The air in the bottle is pushing down on the water, try to get it to escape, but the pressure of the air outside the bottle is also pushing on this water, through the top.

Pressure = Force / Area. Thus the smaller the area, the greater the pressure (for constant force). This is why the area of the gap in the top where the water escapes has to be small. If it was big.. i.e. a pint glass, then it'll just fall out as the pressure of the air isn't enough to keep the stuff in. But i'm sure you knew that!