Ive been asked to do a 50 meter firewalk and was working on what I
would say about the Physics involved. I agree with Leikand that the low
thermal conductivity of the coals is the most important factor as to why
not enough heat is transferred to burn someone, usually. A factor that I
have not seen mentioned though is that before walking on the coals,
which by then are pretty much just carbon, they are always flattened
down, often using the back of a shovel. This gives a flat surface to
walk on that ones feet do not sink into. This morning I also I realized
(duh) that this compacting cuts off the oxygen supply to the lower
coals, not completely, but enough, I'd speculate, to substantially
reduce the rate of heat production. Im thinking this could be quite an
important factor. It seems to me to tie in with my casual observation
that the flattened coals tend to go black after a short time. What do
you good folks think? Thanks for any input generated,
cheers,
David Willey