Density

• Density is the measure of how close and how heavy are the particles of matter in an object. It is measured in kg/m³ or g/cm³ or g/mL.

• Rule for Density

Density (ρ) =	Mass
	Volume

• Example of Density Rule
  
  Q. A stone has a mass of 10 grams. When it is immersed in a measuring cylinder of water, the water level rises 5 millilitres. What is the density of the stone?

A.	Density =	Mass	=	10 grams	= 2 g/mL
		Volume		5 mL

• Densities of Some Common Substances

SUBSTANCE	DENSITY (g/mL)
Air	0.002
Feathers	0.045
Petrol	0.7
Water	1
Aluminium	2.7
Lead	11.3

• Floating and Sinking
  
  The density of water is 1 g/mL. Any substance (such as ice, petrol or oil) whose density is less than 1 will float. Any substance (such as lead) whose density is more than 1 will sink.