state of the union

I went to the APS conference in Pittsburgh. Not much to report on that, it was much as you'd expect, pictures to come. It was intense, I can say that for the experience. There were 7000 physicists in one town for a week. It starts at 8 in the morning and goes till five at night with 3, 3 hour sessions a day, and each of those sessions has 15 to 45 minute mini sessions where each person gives their 'talk'. They tell what their new and exciting research has produced. Then there were evening sessions, dinners, meetings and such. I went to my invited conference on sunday, that was why I went in the first place, and I went to 3 out of 6 sessions on monday and tuesday. The other time I spent in the exhibit hall and then tooling around pittsburgh, blah blah blah. Unless you care about physics you wont care about my trip, but I do have a moderately interesting story to recount.
When I was a waitress I was the queen of tray carrying. I could always carry a full and awkward tray with no spills, mess, or dropping. Its not that I was super talented, I just knew the secret. Occasionally I would meet another waitress who did not know the secret and I would try many different methods with all possible humility and tact to explain it, but without fail, they never appreciated the magnitude of the secret. No matter how much pain and suffering it would save them, they simply were not grateful.
When I was in Pittsburgh I was at a bar by my hotel having dinner and I witnessed yet another waitress making the big tray mistake. Many people when carrying a tray will attempt to place the drinks evenly and equidistant from each other around the whole surface of the tray and then try to precariously hold it at the center of gravity and balance with all their might. Then, not only are they all far away from the center of mass, they all are radially removed from it so they will often have extra velocity than the place at which you are holding it. (think of a record player, the edge of the record makes a circle in the same length of time as the center, but covers a much greater distance, therefore greater velocity). This means it has more momentum and requires greater force to stop, force that you are not applying except to the place where you are holding.
It need not be that difficult at all. The SECRET is to stack all the drinks together in a clump, with the rims of the glasses touching one another. Then not only are they closer to the center of mass, some are even right over it. Also, the force applied when you stop moving is very efficiently applied to all the drinks, and they all have the same velocity and require the same force to stop. Much more stable too, wider base to height ratio.
If you keep that in mind when setting your drinks, you could place the whole clump at the far edge and it doesn't matter as long as you place your hand roughly under the center of the drinks.
So when I saw this young lady making the mistake, it gave me pain. I was tempted, even, to explain it too her yet again. But now, even though I could even explain the physics behind it to her, I still don't think she would have appreciated it.