Why do some objects float and some dont?

Answer 1

Objects float because their density is less than the density of the liquid on which they are resting. In other words if you made a mold of an object and an object weighs less than the water that would fill the mold, the object will float.

Answer 2

Because they have gasses inside like oxygen hydrogen etc. It has to do with water displacement. An object floats because it displaces the water that it sits upon. If it cannot displace this area, it will sink. Displacement means that the weight or volume of a fluid displaced by a floating body, used especially as a measurement of the weight or bulk of boats or ships.

Answer 3

Because the floating object weighs less than the water (or liquid) it displaces. I think this has to do with density. At room temperature water has a density of a little less than 1000 kg/m3. In other words, water weighs 1000 kg for every cubic meter. If an object weighs less for every cubic meter it will float. If it weighs more for every cubic meter it will sink. The same happens with liquids and liquids, solids and solids, gases and gases, gases and liquids, liquids and solids. Steam will rise above the cooler air. Bubbles will rise up through water. Boats sink into the ocean. I'm not sure how this works at a molecular level.