Question

A wooden block floats in glycerine in such a way that it's 2/5th volume remains above the surface.if relative density of wood is 0.78, calculate the relative density of glycerine.

Answer 1

From the laws of flotation

Weight of the wooden block=Weight of the glycerine displaced by immersed portion

(Vwood)(g)(RDwood)=(Vglycerine)(g)(RDglycerine)

(Vwood)(RDwood)=(Vglycerine)(RDglycerine)

RDglycerine=(Vwood)*(RDwood)/(Vglycerine) =(V)*(0.78)/(1−2/5)V =(V)*(0.78)/(3/5)V =1.3