I think it's a quite good document, including the idea of introducing bivectors. At my University, one of the mathematics faculty is excited about introducing bivectors (and much of G.A.) in cooperation with the physics department. Now, we just have to get the high-powered engineering dept. on-board with the whole scheme...
One conceptual problem I *suspect* students will have with the idea of momentum flow as it's presented is the following (I think I can state it as two very intimately entwined concepts, but will let others disentangle these): "If an equal flux of momentum is simultaneously moving from one car, through each bit of string, and through each of the intermediate O-rings, then why aren't the low-mass strings moving very quickly, the larger-mass O-rings moving more slowly, and the large-mass railroad cars moving comparatively slowly? Why doesn't the whole shootin' match break apart? Is this some sort of 'momentum-density-per-unit-length thing?"
________________________________
From: John Denker <jsd@av8n.com>
To: Phys-L@Phys-L.org
Sent: Tuesday, July 23, 2013 6:26 AM
Subject: Re: [Phys-L] force, momentum, torque, and angular momentum
[...]
If you think there are any "more complex problems/concepts"
that are inconsistent with my definition of flow, please
explain. Examples would be particularly helpful. Please be
as specific as possible about the nature of the inconsistency.