free fall activity

[LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>]

        The message which inspired me is quoted at the end.

I am preparing Leigh's chain of ... (are your kids giggling, Herb?)
for today's class. Never heard about this demo before. Sounds like a 
good "explain the paradox" device. I will ask: 

1) Are the distances between the upper nuts different from those at the 
   lower end? By how much in the extreme cases? 
2) How come that what we hear does not match what we see?

We will have about 5 meters available. The upper nut (y=4.9) will take
exactly 1 second to fall. We will have 5 nuts. Where should they be
placed if we want them to hit the floor at equal time intervals, 0.2 s?

y1=4.90  y2=3.14  y3=1.75  y4=0.78  y5=0.196  (or any 25:16:9:4:1 set)

Will try the trick in both of my classes today. Will tell them to expect 
a very similar problem, for a differnt maximum elevation, on the test.
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      On Tue, 16 Sep 1997 Leigh Palmer <palmer@sfu.ca> wrote:

> I do a nice demo [on free fall] with a string onto which have been 
> tied a number of hex nuts at intervals of one, three, five,... units
> starting from its "lower end". The string is suspended vertically
> from its other end with its lower end just touching the bottom of
> an inverted cardboard box which acts as a sounding board. (I must
> stand on a ladder to hold the string.) When I release the string
> the nuts strike the box in a perceptibly constant rhythm. I also
> have a string of nuts tied at constant intervals for comparison.
> This demo is very cheap and easy to perform.