Re: the gem of a day

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

> Date: Tue, 28 Oct 1997 01:19:55 -0500
> From: Hugh Haskell <hhaskell@mindspring.com>
> Subject: Re: A Parents' Day gem
>
> The first question that pops into my mind is, why didn't he do the demo to
> show that they hit at the same time (at least for low velocity situations)?
> Offering to mathematically prove the result just adds fuel to the fire. A
> demo puts it all to rest, and once the parent calms down, then the caveats
> can be added.

And here is one way to perform this well known demonstration (that an object 
pushed horizontally and the one simply dropped from the same height reach
the ground at the same time).

A stone is near the edge of a flat table. One end of a yardstick, resting
on that table, is ready to push the stone horizontally. The other end of the 
yardstick is supporting another stone which is to be dropped vertically. It
is several inches away from the other edge of the table. Push the yardstick 
suddenly and both objects start falling, one nearly vertically and one 
nearly parabolically. And they hit the ground at nearly the same time.

                                Ludwik Kowalski

      Gedankenning is not enough, physics is an experimental science.