Date: Fri, 25 Oct 2002 08:56:33 -0500

Author: "Cliff Bettis"

Subject: Re: Rolling Objects and The Lecture Demonstration Workshop

Post:

Dick,

That's exactly right. We have other objects to vary size and mass; it just
depends on how you want to present it to students. What I like about the set
I had made is that you can pose the question so: here you have a set of
rolling objects of the same rolling radius but different shapes and masses;
we start by arranging them according to mass and then ask how we would
arrange them according to their rolling time down the incline. This is just
the "hook"; there after follows the detailed discussion of moments of
inertia, kinetic and potential energy and why mass and size can be ignored.
Most people will have to see a calculation before feeling very comfortable
talking about the cone and sphere. I found it interesting that all right,
circular cones have the same relationship between their mass and radius
regardless of the apex angle.

Cliff

----- Original Message -----
From: "Dick Heckathorn"
To:
Sent: Thursday, October 24, 2002 8:56 PM
Subject: RE: Rolling Objects and The Lecture Demonstration Workshop


> Greetings,
>
> Is it essential that all be the same size? I was under the impression
> that all spheres roll alike, all cylinders roll alike, all hoops roll
> alike.
>
> My first exposure to this was many years ago when viewing a video by
> Julius Sumner Miller called "rolling things".
>
> Would it not be prudent to first compare spheres of different diameters
> and see they all rolled alike, then cylinders, then hoops, etc?
>
> This being true, one would not need for all to be alike.
>
> Now am I missing something?
>
> Dick
>
> "Science is nothing more than learning how to communicate with nature in
> such a manner that it will talk back."
>
> Helping teachers who facilitate, motivating students who learn.
> Dick Heckathorn 14665 Pawnee Trail Middleburg Hts, OH 44130
> 440-826-0834
> Physics Teacher CVCA 4687 Wyoga Rd Cuyahoga Falls, OH 44224
> 330-929-0575 VM 120
>
>
> -----Original Message-----
> From: owner-tap-l@listproc.appstate.edu
> [mailto:owner-tap-l@listproc.appstate.edu] On Behalf Of Cliff Bettis
> Sent: Thursday, October 24, 2002 4:45 PM
> To: tap-l@listproc.appstate.edu
> Subject: Re: Rolling Objects and The Lecture Demonstration Workshop
>
> Steve,
>
> It isn't complicated: just a cylinder, a ball, a ring, a cone, and a rod
> all, with the help of some light weight discs, having the same rolling
> radius; but it's visually very appealing and makes for very nice concept
> questions. The objects I have all are 4 inches in rolling diameter and
> except for the ball made of aluminum with plastic discs on the cone and
> rod
> to give the proper rolling radius. The ball is a Bocce ball. Dale made
> his
> ball of aluminum but my shop was going to charge me $600 for the ball
> alone
> so I bought a set of Bocce balls and used one of them. You roll the
> objects
> down an incline after asking the audience to order them according to how
> fast they will go down it.
>
> If you want me to I could send a picture.
>
> Cliff
>
> ----- Original Message -----
> From: "Steve Wonnell"
> To:
> Cc: "Steve Wonnell"
> Sent: Thursday, October 24, 2002 2:41 PM
> Subject: Re: Rolling Objects and The Lecture Demonstration Workshop
>
>
> >
> > Cliff,
> >
> > My excuse: I was busy helping out with the laboratory workshops and
> thus
> > couldn't attend the lecture-demo workshop. Advertisement: The lab
> > workshops were also very good and everyone learned quite a bit there
> too.
> > Please attend if you can!
> >
> > So, what is this "Rolling Objects" demo that so tantalizes your folks?
> >
> > Steve W.
> >
> >
> > On Thu, 24 Oct 2002, Cliff Bettis wrote:
> >
> > > Date: Thu, 24 Oct 2002 14:01:31 -0500
> > > From: Cliff Bettis
> > > Reply-To: tap-l@listproc.appstate.edu
> > > To: tap-l@listproc.appstate.edu
> > > Subject: Rolling Objects and The Lecture Demonstration Workshop
> > >
> > > I want to proudly announce the birth of a new demo here. I just got
> back
> a
> > > collection of rolling objects from the machine shop. I was inspired
> by
> the
> > > set I
> > > saw Dale Stille show at the Boise Meeting during the Lecture
> Demonstration
> > > Workshop. Dale also gave me some advice on their construction. The
> set
> was
> > > used in class today for the first time and the Prof was very
> enthusiastic
> > > about them (he's the dept. chairman, by the way, and during an era
> of
> budget
> > > cuts, it doesn't hurt to impress the head guy!).
> > >
> > > It seems that every year I attend the Workshop, I come home with a
> couple of
> > > neat projects. I would encourage anyone no matter what your
> experience
> is to
> > > try to attend one of these workshops. I am sure you will find it as
> > > rewarding a professional experience as I have.
> > >
> > > Cliff Bettis
> > >
> > >
> >
> >
> >
> ************************************************************************
> > Steven K. Wonnell
> > Physics and Astronomy Department E-Mail: wonnell@pha.jhu.edu
> > Johns Hopkins University Phone: (410) 516-4696, 516-5468
> > 3400 N. Charles Street Fax: (410) 516-7239
> > Baltimore, MD 21218-2686 Office: 478 Bloomberg
> >
> ************************************************************************
>

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