Perhaps the best plan is to get hold of the syllabus for the PPL written exams and highlight all the parts of the syllabus that refer to physics (in its wider sense). For example the human performance will almost certainly refer to Boyle's Law, and possibly Dalton's Law.
Then get the syllabus for the flight training, and go through it highlighting all the relevent parts that involve physics. If you stretch a point, most things from dew-point to forces-in-a-turn, to carb-icing can be made to sound relevent. Throw in a few phrases about aerofoils and surface-wind friction effects and a few sentences about the effect of aircraft inertia when encountering windshear and you should be there.
We've not even considered the radio side of things.. ionosphere, interference (wave type) between direct wave and reflected wave giving rise to fading, propagation, etc, the list goes on and on.
What about the engine? Plenty of physics there !
So to start, get hold of the syllabus of the PPL courses you have already done.