Chapter 15, Problem 3PEB

Wood floating in water can demonstrate how the position at which crust floats in the mantle can be estimated from the thickness of the crust and the relative densities of crust and mantle. If a 9.0 cm thick block of wood is placed in a pan of water, determine how much of it will be exposed above water using the density ratio $\left(h=z_{\text{crust}}-z_{\text{crust}}\left({\rho }_{\text{crust}}\right)/{\rho }_{\text{mantle}}\right)?\left({\rho }_{\text{wood}}=0.72g/{\text{cm}}^3\right)$