Rod in freefall
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Nov22-12, 06:57 AM
The inertial force cancels gravity at any point of the rod. Regardless if the origin is in the center or the end: There is no net force on any part of the rod in such a frame, and thus no torque.
That's a good way to look at it (and probably more straightforward).
The extra terms (beyond the torque due to external forces) you get when you calculate dL/dt about an accelerating point are equivalent to introducing that inertial force.