Question

A block of wood floats on water with 1/4 th of its volume above the water surface. The density of the wooden block will be?

Take, density of water = 1 $gc{m}^{-3}$.

• A. 0.25 $gc{m}^{-3}$
• B. 0.50 $gc{m}^{-3}$
• C. 0.75 $gc{m}^{-3}$
• D. 1 $gc{m}^{-3}$

Answer 1

The correct option is C

0.75 $gc{m}^{-3}$

let the volume of the block be V and density of wood be ρ.

The volume of the block above the surface= $\frac{1}{4}V$

The volume of the immersed block (v) =$V-\frac{1}{4}V$= $\frac{3}{4}V$

We know, Weight of the block = weight of water displaced by immersed part of the block.

i.e. V x ρ x g = $\frac{3}{4}V$ x 1 x g

ρ = $\frac{3}{4}$ =0.75 $gc{m}^{-3}$