A large tank of area A contains liquid of density ρ . A cylinder of density ρ4 and length ℓ, and area a (a≪A) is kept in equilibrium by applying an external vertically downward force. The cylinder is just submerged in liquid. At t = 0 the external force disappears instantaneously. Answer the following questions.
The maximum height attained by centre of mass of cylinder from the liquid surface.