It usage guidance says:
... aerodynamics, flight dynamics, stability and control, aircraft hydraulic and electric systems, engine thermodynamics
All of which have their own tags, as they should, so what's the point of aircraft-physics?
To make my point clearer, with an example: the tag system here is not hierarchical; one of the most popular tags in that usage guidance, aerodynamics, has appeared 1,728 times out of 1,826 without aircraft-physics (95% of the time). Further, despite having 299 questions, aircraft-physics appeared on its own only 11 times (SEDE query), and all 11 can be perfectly tagged with more appropriate and well-defined tags.
The usage was ballooned only in 2020, prior to that it was more manageable...
Physics as they apply to aircraft, including aircraft motion, forces affecting an aircraft, and stability and control.
... making it more related to flight-dynamics.
A tag is a word or phrase that describes the topic of the question. Tags are a means of connecting experts with questions they will be able to answer by sorting questions into specific, well-defined categories.