bp's science: upside down cup (or carafe in this case)

My sister recently sent me this picture with the accompanying text, "This carafe accidentally fell of the counter, bounced and landed perfectly like this."

Very cool!?!  I've never seen that before.  Wow!

When this happens, why does it happen?  Why does the water not spill out and make a mess?  Two things:

1. Air pressure: the air pressure in the carafe is lower than the air pressure outside of the carafe and as such keeps the water in the carafe.

[p.s. With regards to pressure, there is also discussion of water's compressibility which, according to the net, is a measure of relative volume change of a fluid as a response to a pressure change.  If you are interested in additional details, click on the links within this parenthetical.]

2. Cohesion and adhesion: a water molecule is polar.  It has a positive and a negative side causing water molecules to stick to each other (cohesion).  Due to this polarity, water is also attracted to other things (adhesion), in this instance, the glass and floor.  These forces keep the carafe from slipping around and falling down.


Disclaimer: The views and opinions expressed in bp's science are those of the author and do not necessarily reflect the official policy or position of any individual scientist, scientific association or the scientific community as a whole. The scientific information provided on bp's science is, at best, of a general nature and cannot substitute for the advice of a licensed or trained scientist, i.e., a competent authority with specialized knowledge who can apply it to a particular set of facts and circumstances. Please contact a local scientific society or similar association of scientists in your area if you require a referral for a particular scientific question or experiment.  Neither the author of bp's science nor anyone else connected to this blog can take any responsibility for the results or consequences of any attempt to use or adopt any of the information or disinformation presented on this blog.