Re: Air Track Experiments

[Richard Tarara <rtarara@SAINTMARYS.EDU>]

Do your air tracks have an 'air pulley' at one end?  If so, a nice set of
experiments is to use a piece of recording tape to connect a mass and the
cart in a 'modified Atwood's machine' configuration.  Use whatever timing
equipment you have to measure _accelerations_.  Vary the falling mass (keep
the system mass constant if you want--move mass from the cart to a mass
hanger used to hold the falling mass) then fix the falling mass and vary the
mass of the cart.  You can use this data directly to confirm N2 given that
the applied force is (mass-falling)xg OR you can assume that the force is
proportional to the falling mass and try to actually 'derive' N2 from the
data.  To do this requires that several sets of fixed falling mass versus
mass of the cart be collected.  Plotting a versus 1/M will be linear but
with different slopes.  Plotting those slopes versus the falling mass
produces a line with an interesting slope and units.  A few suppositions
about the meaning of that slope can then be used to analyze the a versus
falling mass data (fixed system mass) to suggest the functional form for N2.
All this takes a couple weeks of work.

Rick

----- Original Message -----
From: David Abineri <dabineri@CHOICE.NET>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, August 24, 1999 12:19 PM
Subject: Air Track Experiments


> We finally have several air tracks so that we can actually have students
> perform experiments rather than watch demos.
>
> Which air track experiments have worked for you? We have CBL equipment
> available too.
>
> In particular, which is the most meaningful second law experiment for
> students to perform?
>
> Thanks for any suggestions.
> --
>         David Abineri     dabineri@choice.net