Density
Density is a way of comparing how heavy different materials are.
It is a measurement of the amount of a substance contained in a certain The volume of a three-dimensional shape is a measure of the amount of space or capacity it occupies, eg an average can of fizzy drink has a volume of 330 ml..
The density of any solid is the mass of the object divided by its volume.
The formula for density is:
\(\text{density} = \frac{\text{mass}}{\text{volume}}\)
The standard units of density are kg/m3 and g/cm3.
Example
Which material has the largest density?
Aluminium
\(\text{Density} = \frac{\text{mass}}{\text{volume}}\)
\(\text{Density} = \frac{13.5}{5}\)
Density = 2.7 g/cm3
Titanium
\(\text{Density} = \frac{\text{mass}}{\text{volume}}\)
\(\text{Density} = \frac{18}{4}\)
Density = 4.5 g/cm3
Titanium has the largest density. One cubic centimetre of titanium is heavier than one cubic centimetre of aluminium.
The formula for density can be rearranged to calculate the mass or volume of an object.
\(\text{Mass} = \text{density} \times \text{volume}\)
\(\text{Volume} = \frac{\text{mass}}{\text{density}}\)
Question
The density of air is 1.3 kg/m3. Calculate the mass of a balloon which holds 0.0035 m3 of air.
Mass = \(1.3 \times 0.0035\)
Mass = 0.00455 kg