What is Density, What is the SI unit of Density
Another importent term you need to understand in basic physics is Density. Density can be defined as the mass of a material per unit volume. We had already learned that the unit of mass is Kilograms (Kg) and unit of vulume is Meter cube (m3). Since the defenition of density is mass per volume, the SI unit for density is kilogram per meter cube (kg/m3).
To understand the consept of Density, please refer below image.
Density of Iron
To know what is density, let us first try to find the volume of the above Iron cube. In the above image, we have a cube made of Iron having dimensions 1 Meter length, 1 Meter height and 1 Meter width. We can measure the volume of the above cube as Length X Height X Width. In the above case, the volume of a cube with dimensions 1 Meter length X 1 Meter height X 1 Meter width is 1 Meter 3.That is; In above case Volume of the cube = (Length of the cube) * (Height of the cube) * (Width of the cube).
The volume of the above cube is 1 Meter * 1 Meter * 1 Meter = 1 Meter 3.
Now, let us consider that the above cube is made using material Iron. If we measure the Mass am Iron cube having volume as 1 Meter 3, we will get its Mass as 7850 Kilograms.
In other words, if you measure the Mass of Unit Volume of Iron, you will get its Density. Now the concept of Density is clear. If we measure the Mass of a material per unit volume, we will get that material’s density. The Unit of Measurement of Mass in SI Units is Kilograms and the Unit of Measurement of Volume in SI units is Meter 3. So the density of Iron is 7850 Kilograms per Meter 3.
The Density of Iron is 7850 Kilograms per Meter Meter 3.
Density of Copper
Let us try another example to find the volume of the cube made with Copper. As in the case of the cube made with Iron, the cube made of Copper is also having dimensions 1 Meter length, 1 Meter height and 1 Meter width. The volume of the below Copper cube is also 1 Meter 3; that is 1 Meter length * 1 Meter height * 1 Meter width is 1 Meter 3.
Again, if we measure the Mass of a material per unit volume, we will get that material’s density. If we measure the Mass of the above Copper cube having Volume 1 Meter 3 , its Mass will be approximately 8960 Kilograms. So the density of Copper is 8960 Kilograms per Meter 3.