Student Spotlight: density, flotation and the human body

By Stevie Girasole 

Flotation  

Flotation is the phenomenon related to the relative buoyancy of matter. 
Understanding flotation is useful, for example when adding material to the hull of a watercraft to keep the hull afloat. 
Flotation is used in process engineering, as a method for the separation of mixtures e.g de-inking which is a process that takes ink from paper to make it a blank page again.  

Density  

The density (also known as the volumetric mass density) of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used.  

Density or the volumetric mass of density is calculated by dividing the mass of the object by its volume, e.g: 

Mass of object = 5g 

Volume = 10cm3 
Density = mass/volume = 5g/10cm3 = 0.5g/cm3

How does the human body float in water? 

The density of water is 1g/cm3 and the average density of the human body is 1.062g/cm3 so therefore, the human body should not float. But there's an exception to this concept. In the human body, obviously there's extra muscle and fat, in ordinary water, fat will float because of its density of 0.9094g/cm3 so the more fat you have in your body, the more likely you are to float, but, if you have muscle you will sink because of its density of 1.0599g/cm3.  

Well done Stevie!