* Density is a measure of how much mass is packed into a given volume. A substance with a lower density has less mass in the same volume compared to a substance with higher density.
* Water has a density of 1 gram per cubic centimeter (g/cm³).
* Objects with a density less than 1 g/cm³ will float in water because they are less dense than the water they displace. Think of a piece of wood or a balloon filled with air.
* Objects with a density greater than 1 g/cm³ will sink in water because they are more dense than the water they displace. Think of a rock or a metal coin.
In short, if an object floats in water, it has a lower density than water.
