This question asked by me has been put on hold
they say that this question belongs to engineering and not physics.
where should i ask this question ?
edit : how can i modify the question so that my post is back from [ON HOLD] ?
Quite honestly, I think it is a perfectly legitimate question for this site since the answer will be based on fluid mechanics. It doesn't take that many votes to close a question however, and we have a lot of theorists/purists around here. If your approach showed a little more personal effort to understand the effect of the bottle's neck on the exhaust, then it likely would have received an answer and/or not have been closed. Also, it wouldn't hurt to cast the question in the language of fluid mechanics.
We are trying to build a repository of quality questions, and questions which can be typed out in 30 seconds will often be closed; the reason for doing so is somewhat arbitrary.
Currently, there is no place to ask this question. However, there is an Engineering site proposed in Area 51 that you might want to support. They will not answer any questions at this point (still in the "Definition" stage), but this seems like it'd be on-topic on that site (if it goes live).
You did ask a engineering question, although it could have probably been a reasonable physics question if asked properly.
This site seems to be largely about theoretical physics. There is a gray area between engineering and applied physics, but I have noticed that questions that aren't about advanced theoretical physics are treated a lot less well than more advanced questions.
However, I would have probably voted to close your question too, not because of the level of physics or the fact that is about applied physics (I personally enjoy those), but because: