B. A raft of wood (density 600 kg/m) of mas120 kg floats in water. How

1.	B. A raft of wood (density 600 kg/m) of mas120 kg floats in water. How much weight canput on the raft to make it just sink?
Answer» Let us add a mass 'm' kg onto the raft to make it just sink .i.e.,the volume of raft is now completely immersed in water. Let the volume of raft is V which is given by:V= (mass of raft)/(density of raft)=(120/600)m³=0.2 m³. Now this volume is completely immersed in water hence the buoyancy provided by water must balance the weight of raft and the extra mass we have just added. Hence,1000×0.2×g= (m+120)×g.(where 1000 is the density of water in Kg m⁻³ & g is the acceleration due to gravity .) Solving it for mass-'m':-we get m=80Kg.

B. A raft of wood (density 600 kg/m) of mas120 kg floats in water. How much weight canput on the raft to make it just sink?

Answer»

Let us add a mass 'm' kg onto the raft to make it just sink .i.e.,the volume of raft is now completely immersed in water.

Let the volume of raft is V which is given by:V= (mass of raft)/(density of raft)=(120/600)m³=0.2 m³.

Now this volume is completely immersed in water hence the buoyancy provided by water must balance the weight of raft and the extra mass we have just added.

Hence,1000×0.2×g= (m+120)×g.(where 1000 is the density of water in Kg m⁻³ & g is the acceleration due to gravity .)

Solving it for mass-'m':-we get m=80Kg.

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