A hollow cylinder of mass m made heavy at its bottom is floating vertically in water. It is tilted from its vertical position through an angle θ and is left. The respecting force acting on it is

Let l be the length of the cylinder, when vertical, in water. Let A be the cross-sectional area of the cylinder. Equating weight of the cylinder with the upthrust, we get           Mg = Alρg or m = AlρWhen the cylinder is titled through an angle θ, length of cyliner in water = lcos θWeight of water displaced = lcos θAρgRestoring force = lAρgcosθ-lAρg                          = lAρg[1cosθ-1] = mg[1cosθ-1]