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        riddles >> easy >> Problem with Glass Half Full...
        
(Message started by: 2016 on Feb 12^th, 2003, 9:04am)

Title: Problem with Glass Half Full...
Post by 2016 on Feb 12^th, 2003, 9:04am

Well, Forgive the brevity of this post, but my first attempt was destroyed and now I don't have a lot of time.

The problem with both solutions discussed in thread http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_easy;action=display;num=1043895929;start=2 is that they assume that the surface of the water is flat. It is not flat because of the meniscus. Defined by dictionary.com as "The curved upper surface of a nonturbulent liquid in a container that is concave if the liquid wets the container walls and convex if it does not."

Does anyone have a solution that works considering the meniscus?

Title: Re: Problem with Glass Half Full...
Post by aero_guy on Feb 12^th, 2003, 12:22pm

This is what we in aerospace like to call a "higher order effect". We have a very handy way of dealing with terms that are too small, too complicated, or we just don't understand: We ignore them. I think I can safely say that as far as the problem is concerned, the meniscus falls into this category, actually all three. (OK, maybe not the last, but darned if I know the equations to find the curvature of the liquid.) Think of this next time you take an airline flight.

Title: Re: Problem with Glass Half Full...
Post by 2016 on Feb 12^th, 2003, 4:00pm

Yes, it is a higher order effect - but I was struck by the italicized 'accurately' in the riddle as well as the fact that the author of the site called the solution 'sexy.'

Although it is not stated, I also _assume_ that the author means right _circular_ cylinder. There are many 'right cylinders' that would make this problem more challenging.

Anyhoo, I figure you prolly just reeled me in from hyper-anal-rententive world. So, thanks.

Title: Re: Problem with Glass Half Full...
Post by aero_guy on Feb 12^th, 2003, 4:36pm

Hey, someone else is being hyper-anal-rententive? I have a habit for that, and for concentrating on the fifth decimal point when there is a problem with the order of magnitude itself, so I relate. :)