Density

Density

The density of a material is defined as the mass per unit volume.It’s a measure of how tightly the atoms of a material are packed unlike what many would think, density has nothing to do with the hardness of the material or size.  

For example a 1 cm long play-doh surface can be soft and squishy compared to 100 cm long styrofoam. However the density of a 1 cm long play-doh is bigger compare to a 100 cm long styrofoam. We can prove that when we try to float play-doh and styrofoam in water. Styrofoam will float, however play-doh will sunk. This is because the density of play-doh compare to water is bigger eventough it has small volume and no hardness at all. But styrofoam has lower density than water, that is why it will float. The symbol most often used for density is ρ (the lowercase Greek letter rho). Different materials usually have different densities. Solid have the biggest density, because their atom are packed very closely and tight to one another. Then we have liquid, their atom are pack quite closely to one another but the attraction between the atom is not as strong as solid. The last we have air, which have the least density. This is because their atom are far away from one another.

    

where ρ is the density, m is the mass, and V is the volume.

       The units are                      =  kilograms/meter3  =  kg/m3

Examples:

Material	Density (kg/m3)
air	1.29
ice	917
water	1000
aluminum	2700
lead	11300
gold	19300