Dinner Table
inertia - Newton' 1st law - friction
What it shows:
A body will remain at rest unless a force acts upon it. So too will your best china remain
in place as the table cloth is whipped from under it providing the friction between the
cloth and table setting is low, and the speed of removal high.
How it works:
The necessary requirements for a successful removal of the cloth are speed and low friction.
The cloth is a smooth cotton (no hems!) 120 × 50 cm , the dinner setting real
bone china, glass and metal which are nice and heavy so you get the inertia i.e. resistance
to motion. With the long cloth you can make a neat 50 × 50 cm table cloth and
have over half a meter spare to get a good grip of the end. Stand at arm's length to the
bench and take up the spare cloth in folds with both hands so that the cloth beneath the
setting is taut. With one swift, continuous move, bring your hands horizontally into your
body; the cloth comes with them and the setting stays.
Setting it up:
On the end of the lecture bench, lay out the dinner plate, knife, fork and tumbler (a
wineglass is pushing your luck). Let the extra material drape down the side of the bench
ready to be taken up by the lecturer. A correct setting is important (especially at Harvard)
and we recommend studying the reference before the demonstration is attempted.
figure 1. Proper table setting
Comments:
Practice first! The snap removal of the cloth cannot be done timidly. Rating***
References:
Elizabeth L. Post, Emily Post's Etiquette, (Harper Collins 1992) 15th ed., p 426