I'm still having a problem visualizing the positioning stages that John
described, but I was rereading his post on that, and I realized I have
another problem with his thought experiment.
He said to align the moving stages with F1, F2, and F3 respectively, and
adjust their operation so that they accelerate with a1 = F1/m, a2 =
F2/m, and a3 = F3/m. Okay, but they could also be adjusted to F1/k,
F2/k, and F3/k where k is any number.
That means his accelerations are independent of the mass; or stated in
other words... the mass has no bearing on the accelerations he chooses.
That means his accelerations are not uniquely determined by F1 + F2 + F3
= m(a1 + a2 + a3). Therefore I still say he has not shown that a1, a2,
a3 are occurring as specified by F1 + F2 + F3 = m(a1 + a2 + a3); that
is, he has not shown that the specific N2L acceleration for each force
is occurring.
Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu