Question

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)

• A. 80 Kg
• B. 50 Kg
• C. 60 Kg
• D. 30 Kg

Answer 1

Answer: (A)

80 Kg

Answer 2

Volume of log of wood $V = \frac { \text { mass } } { \text { density } } = \frac { 120 } { 600 }$=0.2 m³

Let x weight that can be put on the log of wood.

So weight of the body =

Weight of displaced liquid =

The body will just sink in liquid if the weight of the body will be equal to the weight of displaced liquid.

∴ $( 120 + x ) \times 10 = 0.2 \times 10 ^ { 3 } \times 10$

$\Rightarrow 120 + x = 200$ ∴ x = 80 kg