Date: Fri Aug 3 15:04:20 2007

Author: Jerry DiMarco

Subject: Re: Introduction and question

Welcome aboard. I haven't heard of an experiment quite like the one
you describe. It sounds similar to the DCS demo 4B60.15 - Hammer on Lead,
but with some obvious differences. Have you contacted your alma mater to
see if they're still doing that experiment? A lead disk may work, but I'd
like to know if they used something different. Please let us know if that
is the case...


At 8/2/200708:34 AM, you wrote:
>I just signed up after learning about this list at the Greensboro meeting,
>so I thought I would introduce myself.
>I'm just starting my third year as a tenure-track faculty member at
>Guilford College, a small (~3000 students)
>liberal arts college in Greensboro, North Carolina, so it was fun to have
>the AAPT meeting on my home turf.
>I greatly enjoyed the meeting, not having been to an AAPT meeting before.
>The greatest delight for me was the
>palpable sense of camraderie and mutual willingness to help. Perhaps its
>because we all feel we're on the same
>team, on a mission to make the world a better place. :-) I hope I can be
>as helpful to others as the folks at the
>meeting were to me.
>My question is this: I'm teaching our intermediate lab course for the
>first time this fall, and I was thinking of
>trying to offer a particular experiment to the students. I have vivid
>memories of doing this experiment in my
>own intermediate mechanics course in college. The idea is simple: you
>slide a cart down an air track, and let it
>bounce off a piece of metal at the end of the track. You have a piece of
>a nail stuck in the metal, and the impact
>of the cart drives the nail deeper into the metal. You have a
>thermocouple attached to the metal, and you compare
>the rise in thermal energy of the metal with the decrease in kinetic
>energy of the cart. I remember being stunned
>when the numbers worked out to be equivalent when I did this experiment
>myself, back in, oh, must have
>been 1989. I have almost all the equipment I would need for the students
>to do it here, but I do not remember
>what kind of metal that was that held the nail. It was soft enough for a
>nail to easily sink into it, but not so
>soft that it didn't lose shape or let the nail fall out. As I recall, it
>was a matte grey disc, perhaps the size of
>a quarter, but thicker.
>Does anyone have any recommendations for the best metal to use in this
>experiment and where I might order
>discs like that?
>Thanks, and thanks to those who helped organize the meeting!
>Don Smith