Question

what is density and why it is important.

Answer 1

density is mass per unit volume. it is the amount of mass present in per unit volume. it is important because it is only responsible why some float on water and others sink.

Answer 2

1.A material"s density is defined as the mass per unit volume. It is essentially measurement of how a tightly matter crammed together.
2.The priciple of density was discovered by Archimedes a greek scientist.
3.The S.I unit of density is Kilogram per cubic metre.
4.To calculate 
              density = mass/volume
5.It is frequently represented  in cgs unit of grams per cubic centimeter.