Re: [Phys-l] [PTSOS] anvil and sledgehammer inertia demo

["John Clement" <clement@hal-pc.org>]

This is a case of almost no forces in the horizontal, so it does not show
that balanced forces produce constant motion.

This is the big problem with most of the inertia demos.  Practically all of
the ones that are used have either no forces in the direction of motion or
no motion, which is the case that students believe.

John M. Clement
Houston, TX

> -----Original Message-----
> From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
> bounces@carnot.physics.buffalo.edu] On Behalf Of Joseph Bellina
> Sent: Wednesday, September 29, 2010 3:38 PM
> To: Forum for Physics Educators
> Subject: Re: [Phys-l] [PTSOS] anvil and sledgehammer inertia demo
>
> Ever go bowling?
>
>
> Joseph J. Bellina, Jr. Ph.D.
> Emeritus Professor of Physics
> Co-Director
> Northern Indiana Science, Mathematics, and Engineering Collaborative
> 574-276-8294
> inquirybellina@comcast.net
>
>
>
>
> On Sep 29, 2010, at 3:26 PM, ludwik kowalski wrote:
>
> > On Sep 29, 2010, at 3:15 PM, Stefan Jeglinski wrote:
> >
> > > > The really important demo is to show that a moving object
> > > > with balanced forces remains in constant motion.
> > >
> > > I substantially agree. What are your favorite demos of this, suitable
> > > for a classroom?
> >
> > The first thing that came to my mind was driving a car
> > horizontally. I press the gas pedal too strongly and the car
> > accelerates; I press it much less strongly and the car slows down.
> >
> >
> > http://csam.montclair.edu/~kowalski/life/intro.html
> >
> >
> >
> >
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