Re: Physics of an arch?

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

> One of my colleagues just emailed me a question that I am having
trouble
> answering.  I hope I can garner some help here...
>
> She is a classics professor, and wants to better understand the
> mechanics/physics of a classical arch built out of stone.  How do
they
> stay together, some of them without mortar?  What is the
significance of
> the keystone, and how do the forces interact to make it important.
>
> Now I know this must've been studied, but I can't find a reference
in
> any of my mechanics textbooks.  Does anyone have a reference I can
use
> to explain this and/or point her toward?

The free body digram, for each block,
should have three forces: m*g pointing
down and the reaction force from each
of the two neighbors. The net force on
each block should be zero. The depth
of each block is presumably large
enough to eliminate the possibility of
sidewise motion. The same applies
to the top stone (keystone).

Shapes of stones should match the
desired radius of curvature.  Make
several wooden blocks to illustrate
the main idea.

the
adjacent blocks