Let's say you had a hollow metal cube. A hole is drilled through the side, and a straw is put in. The only way for anything to get in or out is through the straw. The container is filled fully with water. Is it possible to get the water out by suction?

I thought of this question after watching a VSauce video where he said the following: You don't really suck liquids up through a straw, you just cause the air in your mouth to push against it, through the straw less than usual.

Obviously, I know that in real life, the container flexes, and some water can be sucked through. However, in an unflexing container, can the water be sucked out?

  • $\begingroup$ Possibly relevant: physics.stackexchange.com/questions/604543/… $\endgroup$
    – Andrew
    Jul 21, 2022 at 1:07
  • $\begingroup$ You may not even be able to pour fluid out of a container that way if fluid trying to flow out of the container can't find it's way around the air trying to flow in. $\endgroup$
    – DKNguyen
    Jul 21, 2022 at 2:48
  • 2
    $\begingroup$ This is something you can easily try for yourself. Get one of those hard plastic tumbler cups like this ebay.com/itm/143514566546, duct tape over the small air hole(s) in the lid, and see what happens. $\endgroup$
    – RC_23
    Jul 21, 2022 at 4:18
  • $\begingroup$ (assuming the straw dosen't flex) keep this cube with straw inside a vacuum chamber :) $\endgroup$ Jul 21, 2022 at 4:51

1 Answer 1


No. If the air can't get in the container in any way other than the straw than you won't get any water. A tiny amount of water may go up the straw a bit but it wouldn't be a reasonable amount to drink. This is because when you suck on the straw the air around it pushes on the water, to fill the vacuum. The water can climb up a bit, but it won't be able to support it's own weight without the pressure of the air.


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