Modeling physics has adopted Bruce's approach. Big F, 3 subscripts. One for the category (N, G, f, e, T) then one for the 'dealer' and one for the 'feeler.'
In addition to reducing fictional forces (the force on the object because it is moving etc...) it also helps with N3L pairs.
Paul.
-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Bruce Sherwood
Sent: Tuesday, December 10, 2013 12:13 AM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] sharing an activity re circular motion free-body diagrams
Glad you like the approach, Alex.
In June of 2010 the Computer History Museum in Mountain View, California, hosted a two-day retrospective on the PLATO computer-based education project developed at the University of Illinois. There were various sessions on hardware, system software, games, etc., and a session chaired by Ruth Chabay on "courseware" -- tutorials developed for the PLATO environment. In the video of this session, found at
the ten-minute segment that starts at 45:43 is a presentation by me of an interactive graphics-oriented tutorial on free-body diagrams that I wrote in 1970 (!) that incorporates among other aspects having students name the objects in the surroundings that exert forces on the chosen system. This was written up in my article "Free-body diagrams (A PLATO lesson)", American Journal of Physics 39, 1199-1202 (1971). The tutorial was part of a PLATO-based mechanics course whose development I led.
This and other conference videos mentioned at the YouTube site will be of interest to anyone interested in the history of computers, and of their application to education, as the PLATO system was very far ahead of its time. For example, we were using flat plasma-panel displays in the early 1970s, with 512 by 512 resolution and 16 by 16 touch sensitivity.