Students can find the density of an object using the formula:
d=m/v
where d=density, m=mass and v=volume.
The object can be anything small enough to fit into a measuring cylinder such as a small stone, blob of
plasticine, lego brick etc.
Firstly the student can find the mass of the object by placing it on a pan-top balance or by using a spring
balance (see Fig 1) Then the object is placed into a measuring cylinder half filled with water
(see Fig 2). The water it displaces is equal to its mass. A eureka can can be
used instead of a measuring cylinder for this practical.
To find the density of the object, the mass is simply divided by the volume. The result is measured in
kg/m³.
Equipment required (per set):
- An object (stone, plasticine etc)
- Measuring cylinder or density (eureka) can
- Pan-top balance or spring balance
Geologists sometimes use this method to find the density of rocks. This helps them identify its type.