In connection with the FCI there was some commentary on Newton's 3rd law.
I'll mention that I learned from Fred Reif a useful, nontraditional way of
approaching the subject. Point out the "reciprocity" of the gravitational
and electric force laws: m1m2 = m2m1 and q1q2 = q2q1. From this it is clear
that the magnitudes of the two forces must be the same. A further step is
to view the contact between the big truck and the little car at the atomic
level, where one expects the interatomic forces to obey reciprocity since
they are electric in nature. This approach gives a sense of mechanism that
is lacking from the convoluted English-language version of the 3rd law.
The more fundamental view is that momentum must be conserved, so that the
changes in the momenta of the truck and car must have the same magnitude
and opposite sign. An interesting point is that magnetic forces do not
necessarily obey the reciprocity relationship. Consider an instant when a
proton is at the origin headed in the +x direction, and an electron is
somewhere along the +x axis headed in the +y direction. The proton
contributed zero magnetic at the location of the electron and hence there
is no magnetic force acting on the electron, whereas the electron does
contribute a magnetic field at the location of the proton, and there is a
magnetic force acting on the proton. Hence the total particle momentum of
the isolated proton+electron system changes despite there being no net
external force on the system. Momentum however is conserved: there is a
change in the momentum associated with the fields, and the total momentum
of the universe doesn't change.