Re: Hewitt blew it again

[Jack Uretsky <jlu@HEP.ANL.GOV>]

        Ideally, you want to use a magnetic release such as are used
with the demo of the monkey and the hunter.  Failing this, you might
try having a person do several drops of free masses and get some
statistics on time intervals between contact with the floor of the
free masses.  This will give you a measure of the resolution of your
experiment.
        The free mass data with different size masses will give you
a nice check on Galileo, who was known to be very unreliable.
                                Regards,
                                        Jack

Adam was by constitution and proclivity a scientist; I was the same, and
we loved to call ourselves by that great name...Our first memorable
scientific discovery was the law that water and like fluids run downhill,
not up.
                          Mark Twain, <Extract from Eve's Autobiography>

On Mon, 10 Jan 2000, Leigh Palmer wrote:

> I received my January Physics Teacher today, a very long delay.
> I've reread Hewitt's "Answer" and I find it completely
> unsatisfactory. If Hewitt is correct, his answer should end at
> "Block B hits the floor first." Nothing he says after that is
> the least bit illuminating; he hasn't conveyed the concept to
> me, at least, and I don't think I'm the least teachable person
>
> Jack Uretsky suggests that the catenary profile of the chain is
> important to this putative effect. I will try the experiment
> again, but I intended to perform it in a different manner, with
> the chain initially belayed below the drop point. This will
> give me double the height that can be had with Hewitt's setup.
> I will use a video camera (1/60 s per field) and an exposure
> time of 1/10,000 s to do the timing. I have not been able to
> come up with a simple method of starting the ball and the end
> of the chain at the same time, and I'm open to suggestions. I
> will, of course, drop the several times.
>
> To achieve symmetry I have obtained a plastic chain and a steel
> ball, the complement to Chuck Britton's apparatus. The catenary
> shown in Hewitt's cartoon has an aspect ratio of about four. I
> used a much skinnier catenary in my first experiment. I thought
> the result would be insensitive to that parameter, as the case
> of the bungee must surely be so.
>
> Any suggestions? I use a 500 W quartz halogen lamp to take
> video at 1/10,000 s.
>
> Leigh