Hi guys, I'm retaking Unit 2, and been analysing past papers. I reckon the 6 marker will be on either energy transformations, diffraction, TIR/light stuff, or possibly something fairly unusual going by Unit 1's 6 marker. I highly doubt it will be stationary waves or Young modulus etc, because that's come up a lot recently. Might well be an experiment we have to describe, possibly springs? This is only my best guess though.
Best of luck everyone!