Anyway, you don't have to study Physics to be able to do it , I just wanted to say that every time you change your stoping position(where you pinch the note in this case) you change the number of the overtone(change the note)...
In other words, you'll find places that works for P.H. and others that won't work (bec they are unclear), your job is to be able to find the right spots that suits the fretted note you're playing.