Why does a denser object sink?

A denser object sinks because it has a greater mass per unit volume compared to the fluid it's placed in. When the density of the object exceeds that of the fluid, the gravitational force acting on the object is greater than the buoyant force exerted by the fluid, causing it to sink. This principle is rooted in Archimedes' principle, which states that an object submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by it.