A raft of wood (density 600 kh/m ³ ) of mass 129 kg floats in water. How much weight can be put on the raft to make it just sink ?

$$\begin{gathered} \mathrm{Volume} \mathrm{of} \mathrm{the} \mathrm{raft} \\ =(129/600)=0\cdot 215{\mathrm{m}}^3 \\ \mathrm{Weight} \mathrm{of} \mathrm{water} \mathrm{displaced} \mathrm{whe}n \mathrm{it} \mathrm{sinks} \\ =0. 215 \times {10}^3 \times 9.8 N = 2107 N \\ \mathrm{Hence} \mathrm{additional} \mathrm{weight} \mathrm{to} \mathrm{be} \mathrm{placed} =( 2107 - 129\times 9.8 ) N= 842.8 N \end{gathered}$$.Hence additional mass to be placed = $\frac{842.8}{9.8}kg =86 kg$