1. The problem statement, all variables and given/known data http://www.physics.ox.ac.uk/olympiad/Downloads/PastPapers/BPhO_PC_2008_QP.pdf Question 6 2. Relevant equations Moment = Force * Distance moved 3. The attempt at a solution I have tried this and I am sorry to say that I have no idea how to work it out. I think it is something to do with moments but the centre of gravity is not about a pivot so I don't if I should still reference Y from W. Furthermore, since the exact location of W is not known, I can't just use pythagoras to find the distance of Y from W. Any help would be great, thank you very much.