A log of wood of mass 120 Kg floats in water. The weight that can be put on the raft to make it just sink, should be (density of wood = 600 Kg/m3)

Volume of log of wood  V=massdensity=120600=0.2 m3Let x weight that can be put on the log of wood. So weight of the body =  (120+x)×10 NWeight of displaced liquid  =   Vσg=0.2×103×10 NThe body will just sink in liquid if the weight of the body will be equal to the weight of displaced liquid.∴ (120+x)×10=0.2×103×10⇒120+x=200 ∴x=80kg