Re: [Phys-l] possible projectile lab

[Jack Uretsky <jlu@hep.anl.gov>]

	Galileo came from a musical family, and I have read that musical 
rhythm played a role in his timing mechanism; also, that he used his pulse 
as a clock for timing purposes.
	My post, and this response, emphasize some of the experimental 
difficulties in attempting to reproduce what Galileo said he did.
	Well, Newton is known to have dry-labbed some of his 
"expeerimental"  results, so why not Galileo.  He was not the first to 
realize that objects fall with constant acceleration.
				Regards,
					Jack

"Trust me.  I have a lot of experience at this."
		General Custer's unremembered message to his men,
		just before leading them into the Little Big Horn Valley




On Sat, 19 Dec 2009, LaMontagne, Bob wrote:

> I use a flat board about 2 meters long. I carefully attach to it 2 meters of HO scale model railroad track (can be bought in 1 meter sections - called flex-track). The students and I roll 2 inch chromed steel balls down the tilted track and board. We place dominoes on the track and let the heavy balls strike the dominoes and tip them over. We move the dominoes until we hear them fall at a steady cadence - clapping your hands as the dominoes fall makes it easy to tell if the rhythm is steady. The distances invariably show a direct proportionality with the square of the "clicks" when the the dominoes fall. The distances between dominoes increase proportional to the odd integers as expected.
>
> Bob at PC
>
> Physics: Fair and Balanced
>
> ________________________________________
> From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Jack Uretsky [jlu@hep.anl.gov]
> Sent: Friday, December 18, 2009 11:00 PM
> To: Forum for Physics Educators
> Subject: Re: [Phys-l] possible projectile lab
>
> Hi all-
>        I tried repeating Galileo's experiment in a lab at College of
> DuPage, about 10 years ago.  The problem was to find a sufficiencly smooth
> plank of wood to use as an inclined plane.  We never had an acceptable
> reproduction of Galileo's result.
>                                Regards,
>                                        Jack
>
> "Trust me.  I have a lot of experience at this."
>                General Custer's unremembered message to his men,
>                just before leading them into the Little Big Horn Valley
>
>
>
>
> On Thu, 17 Dec 2009, Bernard Cleyet wrote:
>
> > In the Florence museum:
> >
> > http://brunelleschi.imss.fi.it/museum/esim.asp?c=404013
> >
> > Not a duplicate of the original.
> >
> > bc been there saw that, and his finger.
> >
> >
> >
> >
> > On 2009, Dec 16, , at 20:47, Gary Karshner wrote:
> >
> > > Dwight,
> > >     This is a real classic in the sense that Galileo used it to study
> > > accelerated motion. He found the distance covered by the marble down
> > > an
> > > inclined plane varied as the square of the time. He measured the time
> > > intervals by using a series of frets that the marble would pass over
> > > with a
> > > bump or ticking sound. He arranged the frets so the ticking was on the
> > > musical beat thus placed at equal time intervals. Stillman Drake in
> > > his book
> > > "Galileo at work" repeated the experiments from Galileo's notes. He
> > > also
> > > wrote an article in Scientific American describing this work, in the
> > > 1970's
> > > I think.
> > >      Galileo then goes on to calculate where the marble will land,
> > > and that
> > > then end of his experiments on falling bodies. The kicker is that
> > > the marble
> > > doesn't land where he expects because of the kinetic energy stored
> > > in the
> > > rolling ball. He used the motion down the plane to determine the
> > > acceleration of gravity.
> > >      So your experiment is true a classic one. good luck with it.
> > > Gary
> > > _______________________________________________
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