Gravitational Potential Energy

When a wooden cube is floating in water, the fraction of the cube immersed is determined by the balance of buoyant force and weight. The buoyant force depends on the apparent weight of the block, which is reduced when the lift moves downward. In the downward motion, the effective gravity acting on the block is reduced to . However, the fraction of the cube immersed remains the same because the buoyant force still exactly balances the cube's weight in the lift, which is now halved. Thus, the fraction of the cube immersed remains unchanged as .