Final answer:
The common factor among floating objects is their density being less than that of the fluid, allowing them to displace enough fluid to support their weight. Sinking objects have a greater density and cannot displace enough fluid to prevent them from being submerged, although they are still partly supported by buoyant force.
Step-by-step explanation:
The tendency for objects to float or sink in a fluid is primarily due to the objects' density relative to the fluid in which they are submerged. Archimedes' principle states that the buoyant force on an object in a fluid is equal to the weight of the fluid displaced by the object. This principle provides a basis for understanding the buoyancy of objects.
For floating objects, one common characteristic is that their overall density is less than that of the fluid they are in. Hence, they displace an amount of fluid equal to their weight before being completely submerged. An example of this is a boat: a lump of clay shaped into a boat can float because it displaces more water than when it was just a lump, thus experiencing greater buoyant force.
Meanwhile, sinking objects, such as an anchor, have a density greater than the fluid. They sink because they are unable to displace an amount of fluid equal to their own weight before being completely submerged. However, they are still partly supported by the water, as some buoyant force is still exerted on them.