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/m)

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

Answer 1

The correct option is A 80 kg

Let volume of wood $=$v

Weight $=\int$ wood vg

$120g=600vg$

$v=\frac{1}{5}{m}^3$

Let mass added be 'm'

Total weight$=$Bowyancy

$\int$ wood $vg+mg=\int$ want Vg

$600vg+mg=1000vg$

$mg=400vg$

$m=400\times \frac{1}{5}$

$m=80$kg

Option (A).