Re: [Phys-L] kinematics objectives

[jbellina <inquirybellina@comcast.net>]

You can do the same thing. With paper plates. I do 1 vs 10. The result is obvious even after a meter

Joe

Sent from my iPhone

On May 9, 2013, at 9:43 PM, Bill Nettles <bnettles@uu.edu> wrote:

> I have demonstration in which I "prove" that Aristotle is right about heavier objects falling faster.  I have three squares 10 cm x 10cm: one of cardboard, one of aluminum and one of lead. I drop them in pairs, flat side facing the ground. Lead wins every time.  You have to drop from about 2.5  meters to make it obvious that it hits before the aluminum.  Then we talk about air resistance, shape profiles, and a_air=F_air/m so that the more massive object has less acceleration upward due to air.  Then I take two sheets of paper, let them both drift to the floor, then crumple one and release them again.
>
> I've tried dropping the squares with the edges facing down, but the cardboard flips too easily.
>
> > -----Original Message-----
> > From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Philip Keller
> > Sent: Thursday, May 09, 2013 5:07 PM
> > To: Phys-L@Phys-L.org
> > Subject: Re: [Phys-L] kinematics objectives
> >
> > JD wrote:
> >
> > By telling students their ideas are not crazy wrong, just /restricted/, they are
> > less likely to get defensive.
> >
> > ------
> >
> > That made me remember something from one of my first years teaching. I
> > was presenting some of what Aristotle had to say about motion as in
> > introduction to Newton's laws.  I was about 10 minutes in when one of my
> > students raised his hand to interrupt:  "Wait.  Are you saying that this stuff is
> > WRONG?"   I said it was...and he said "but this is the first thing you've said all
> > year that I understand!"
> >
> > Ever since then, I have made it a point to acknowledge that it is completely
> > reasonable to believe that the natural state of an object is to be at rest.  If
> > you had to use your personal experience to choose between Galileo and
> > Aristotle, Aristotle would win.
> >
> > Similarly, it is just as reasonable to believe that the Sun goes around the Earth
> > as do the stars.  Aristotle was not a dumb guy. Neither were those ancient
> > Greeks.
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