A cubical metal block \(5\,cm\) on each side is floating in mercury in a vessel. Now, a liquid is gently poured into the vessel so that it just covers the metal block as shown. What is the depth of the liquid that has been poured over the mercury?
Given:
\[
\rho_{\text{Hg}}=13.6,
\qquad
\rho_{\text{metal}}=7.6,
\qquad
\rho_{\text{liquid}}=1.6
\]