Question

a wooden block floats in glycerine in such a way that its 2/5 th vol. remains above surface.if relative density of wood is 0.78 calculate the relative density of glycerine. plz explain.

Answer 1

Volume of block = V

Volume of water displaced = V - 2V/5 = 3V/5 = 0.6V

Density of wood (d) = 0.78 × 1 g/cm³ = 0.78 g/cm³

Density of glycerine = d’

Weight of block = Buoyant Force

Vdg = 0.6Vd’g

d’ = d / 0.6

d’ = 0.78 g/cm³ / 0.6

d’ = 1.3 g/cm³

Relative density of glycerine = 1.3 g/cm³ / (1 g/cm³)

= 1.3

Relative density of glycerine is 1.3