Hi David,
There is no need to resort to scientific explanations, theory and hypotheses - I feel they detract from the "real" lesson at hand. Always in simple non-esoteric terms.... as my teachers taught.
Like Mr Miyagi (God bless his soul) showing Daniel-san the secret of his family's karate....
PS: FWIW, Patrick McCarthy never used physics to explain what he was doing... always very simple explanations, so the principle was easily and quickly grasped. You don't need to confuse the student any further with all that high-falutin theoretical claptrap....