Answer to Question #281338 in Physics for haasggdfnsd

Question

A rod 0.5 m long floats vertically in a liquid with 0.3 m above the surface. What is the density of the rod if the relative density of the liquid is 1.2?

Answer 1

Given:

$\rho_L/\rho_W=1.2$

$l=0.5\:\rm m$

$l_{\rm sub}=0.2\:\rm m$

The equilibrium condition gives

$F_{\rm buoyant}=mg$

$g\rho_Ll_{\rm sub}A=g\rho lA$

$\rho=\rho_L l_{\rm sub}/l=\rm1200\: kg/m^3*0.2/0.5=480\:kg/m^3$