Question

A cube of wood supporting 200gm mass just floats in water. When the mass is removed, the cube ruses by 2cm. What is the size of the cube?

Answer 1

Correct Answer - A::C
Let the edge of cube be l. When mass is on the cube of wood
`200g+l^3d_(wo od)g=l^3d_(water)g`
`impliesl^3d_(wo od)=l^3d_(water)-200` …(i)
When the mass is removed
`l^3d_(wo od)=(l-2)l^2d_(water)` …(ii)
From (i) and (ii)
`l^3d_(water)-200=(l-2)l^2d_(water)`
But `d_(water)=1`
`:.l^3-200=l^2(l-2)impliesl=10cm`