1. The problem statement, all variables and given/known data A thin wooden plank 1m long is kept on the protruding stone with some of its part immersed in water. Will the centre of gravity of the wooden plank be inside the water or outside? 2. Relevant equations 3. The attempt at a solution For the wooden plank to be in equilibrium, moments of buoyancy force and weight about the point of contact of stone should be equal. Buoyancy force acts at the midpoint of the immersed part. But what will be the position of the centre of mass (gravity) of the plank?