How is density used in real life?

Answer 1

Density has its connection with buoyancy.The ability of an object to "float" when it is placed in a fluid is called buoyant force. If an object is less dense than the fluid in which it is placed, it will "float" on the fluid. If it is more dense than the fluid, it will "sink."

For example:

Metal ships can float because their total density is less than that of the water that they float on.