Date: Wed, 13 Feb 2002 10:14:17 -0600 (CST)

Author: Paul Nord

Subject: Re: heat transfer


Do let us know how that goes! And take a video.

I've been wanting to do this one for a long time, but I don't have the

As I heard the story, the army stood in more of a parabolic arc. This was
to gain more intensity from the multiple reflections.

That said... I'm still not sure how important it is to stand in an arc. I
would think that you could just stand in any formation that would give
each person a clear view to the target. At a good distance, a 1 foot
mirror is essentially a pinhole camera. It will focus a clear image of
the sun. That's more convincing when there's an eclipse going on. But it
works very well.

Perhaps you could test various configurations.

Also, tell us how you mark off the geometry for large formations. And, do
tell how long it took.


On Wed, 13 Feb 2002, James Braunsdorf wrote:

> I have not had time to try this idea but I think it could be dramiatic if it
> works. It is based on the tale that Archimedes(as I recall) had soldiers
> with polished shields set fire to the sails of enemy ships that were
> attacking.
> I have a bunch of foot square mirrors that are sold for tiling walls. I
> would set a cardboard box on the ground with the open side facing north and
> a piece of black paper taped inside the opening to hang down as a target.
> (This being to avoid drafts and keep too much convection effects down.)
> then let the class members stand in an arc and reflect sunlight from about
> twenty mirrors on the black piece of paper.
> I would expect that it would heat up rapidly.
> Jim Braunsdorf
> Mishawaka High School
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